Deoxygenation of fatty acids for preparation of hydrocarbons

ABSTRACT

Embodiments of methods for making renewable diesel by deoxygenating (decarboxylating/decarbonylating/dehydrating) fatty acids to produce hydrocarbons are disclosed. Fatty acids are exposed to a catalyst selected from a) Pt and MO 3  on ZrO 2  (M is W, Mo, or a combination thereof), or b) Pt/Ge or Pt/Sn on carbon, and the catalyst decarboxylates at least 10% of the fatty acids. In particular embodiments, the catalyst consists essentially of 0.7 wt % Pt and 12 wt % WO 3 , relative to a mass of catalyst, or the catalyst consists essentially of a) 5 wt % Pt and b) 0.5 wt % Ge or 0.5 wt % Sn, relative to a mass of catalyst. Deoxygenation is performed without added hydrogen and at less than 100 psi. Disclosed embodiments of the catalysts deoxygenate at least 10% of fatty acids in a fatty acid feed, and remain capable of deoxygenating fatty acids for at least 200 minutes to more than 350 hours.

FIELD

Disclosed herein are embodiments of fatty acid deoxygenation(decarboxylation/decarbonylation/dehydration) catalysts and methods ofmaking and using the same.

BACKGROUND

The terms “green diesel” and “renewable diesel” broadly refer todiesel-quality, non-FAME (fatty acid methyl ester) fuels derived fromrenewable resources (e.g., plant and/or animal sources) that aresuitable for direct use in most ordinary compression ignition dieselengines. Renewable diesel is chemically distinguishable from biodiesel,which is primarily composed of fatty-acid-derived mono alkyl esters. Theoxygen content of biodiesel is too high to be suitable as a directreplacement for conventional petroleum diesel. In contrast, renewablediesel is substantially oxygen-free and is indistinguishable frompetroleum diesel. Thus, renewable diesel can replace petroleum dieseland/or be used in blends with petroleum diesel. Renewable diesel alsohas higher energy content per volume compared to biodiesel. Renewablediesel may be used or blended in aircraft fuel where oxygen-containingfuels are not allowed.

Conventional processes for converting renewable oils or fats, such asvegetable oil or animal fat, to renewable diesel include catalytic orthermal decarboxylation (removal of carbon dioxide), catalyticdecarbonylation (removal of carbon monoxide) and catalytichydrocracking. The products are expected to be simple hydrocarbons orolefins. The feed for these processes can be a triglyceride or a freefatty acid.

Commercially available deoxygenation catalysts suffer from severaldisadvantages such as poor stability, low activity, undesirable sidereactions, and/or a need to operate under high pressure conditions inthe presence of hydrogen gas.

SUMMARY

Embodiments of methods for making renewable fuel (such as renewablegasoline, renewable diesel, or renewable aviation fuel) by deoxygenatingfatty acids to produce hydrocarbons are disclosed. Embodiments of highlyactive, selective catalysts for deoxygenating fatty acids andembodiments of methods for making and using the catalysts also aredisclosed. The disclosed catalysts comprise a Group VIII metal, asupport material, and a transition metal oxide or a non-transitionmetal. In particular embodiments, the Group VIII metal is platinum. Thesupport material is carbon, a metal oxide, or a metalloid oxide. In someembodiments, the support is a metal oxide, and the catalyst furtherincludes a transition metal oxide. In other embodiments, the support iscarbon, and the catalyst further includes one or more non-transitionmetals (e.g., Ge, Sn, Pb, Bi).

In certain embodiments, the catalyst is MO₃/Pt/ZrO₂ where M is W, Mo, ora combination thereof, Pt/Ge/C, Pt/Sn/C, or a mixture thereof. In someembodiments, the catalyst comprises 0.1 wt % to 1.5 wt % Pt and 6 wt %to 30 wt % MO₃ on ZrO₂, relative to the total mass of catalyst. In oneembodiment, the catalyst comprises 0.7 wt % Pt and 12 wt % WO₃ on ZrO₂.In another embodiment, the catalyst consists essentially of 0.7 wt % Ptand 12 wt % WO₃ on ZrO₂. In one embodiment, the catalyst comprises 0.7wt % Pt and 7.8 wt % MoO₃ on ZrO₂. In another embodiment, the catalystconsists essentially of 0.7 wt % Pt and 7.8 wt % MoO₃ on ZrO₂. In otherembodiments, the catalyst comprises 1 wt % to 5 wt % Pt and 0.1 wt % to5 wt % Ge and/or Sn on carbon. In certain embodiments, the catalystcomprises a) 5 wt % Pt and b) 0.5 wt % Ge, 0.5 wt % Sn, or 0.5 wt % of acombination of Ge and Sn, relative to the total mass of the catalyst. Inparticular embodiments, the catalyst consists essentially of a) 5 wt %Pt and b) either 0.5 wt % Ge or 0.5 wt % Sn on carbon, relative to thetotal mass of the catalyst.

Embodiments of methods for deoxygenating fatty acids with the disclosedcatalysts are also disclosed. In one embodiment, fatty acids are exposedto a catalyst selected from a) Pt and MO₃ on ZrO₂ where M is W, Mo, or acombination thereof, or b) Pt/Ge or Pt/Sn on carbon, and the catalystdeoxygenates at least 10% of the fatty acids in a fatty acidcomposition. Some embodiments of the disclosed catalysts deoxygenate atleast 80% of the fatty acids.

The fatty acids are obtained from a plant oil, a plant fat, an animalfat, or any combination thereof. In some embodiments, at least 90% ofthe fatty acids in the fatty acid composition are saturated fatty acids.In certain embodiments, the catalyst comprises 0.1-1.5 wt % Pt and 6-30wt % MO₃ on ZrO₂, where M is W, Mo, or a combination thereof, relativeto a total mass of the catalyst. In one embodiment, the catalystconsists essentially of 0.7 wt % Pt and 12 wt % WO₃ on ZrO₂, relative tothe total mass of the catalyst. In another embodiment, the catalystconsists essentially of 0.7 wt % Pt and 7.8 wt % MoO₃ on ZrO₂, relativeto the total mass of the catalyst.

In other embodiments, at least some of the fatty acids are unsaturatedfatty acids having one or more double and/or triple bonds. In certainembodiments, the catalyst comprises a) 1-5 wt % Pt and b) 0.1-5 wt % Ge,0.1-5 wt % Sn, or 0.1-5 wt % of a combination of Ge and Sn on carbon,relative to a total mass of the catalyst. In particular embodiments, thecatalyst consists essentially of a) 5 wt % Pt and b) 0.5 wt % Ge or 0.5wt % Sn on carbon, relative to the total mass of the catalyst. In someembodiments, exposing the unsaturated fatty acids to the catalystresults in cyclization and/or aromatization of up to 10% of the fattyacids. In certain embodiments, exposing the unsaturated fatty acids tothe catalyst results in isomerization, cracking, alkylation, cyclizationand/or aromatization of greater than 10% of the fatty acids.

In some embodiments, the fatty acids in the composition are free fattyacids, fatty acid esters, fatty acid monoglycerides, fatty aciddiglycerides, fatty acid triglycerides, or any combination thereof. Incertain embodiments, at least 90% of the fatty acids in the fatty acidcomposition are free fatty acids. The free fatty acids can be obtained,for example, by hydrolyzing triglycerides or fatty acid esters. In someembodiments, triglycerides are hydrolyzed to produce free fatty acidsand glycerol. In certain embodiments, the free fatty acids are separatedfrom the glycerol, and the glycerol is recovered. In some embodiments,the fatty acids include unsaturated fatty acids, and the unsaturatedfatty acids are hydrogenated before exposure to the catalyst. Inparticular embodiments, triglycerides comprising unsaturated fatty acidsare hydrogenated before hydrolyzing the triglycerides to produce freefatty acids and glycerol.

In certain embodiments, deoxygenation is performed at a temperature ofat least 250° C. In one embodiment, the fatty acid composition ispreheated to a temperature of at least 50° C. before exposure to thecatalyst. In another embodiment, the composition is not preheated beforeexposure to the catalyst. In yet another embodiment, the composition isheated in the presence of the catalyst at a temperature of at least 50°C., and deoxygenation is performed subsequently at a temperature of atleast 250° C. In another embodiment, the composition is exposed to afirst catalyst in a first catalyst bed at a temperature of at least 50°C., and at least 10% of the fatty acids are deoxygenated by subsequentlyexposing the composition to a second catalyst in a second catalyst bedat a temperature of at least 250° C. The first and second catalysts mayhave the same or different chemical compositions.

In certain embodiments, the catalyst is disposed within a column, andthe composition is flowed through the column. In particular embodiments,deoxygenation is performed without added hydrogen and/or at a pressureof less than 250 psi. In one embodiment, deoxygenation is performed atless than 100 psi. In another embodiment, deoxygenation is performed atambient pressure. In some embodiments, the fatty acids are flowedthrough a column at a weight hourly space velocity of 0.1-2.0 hr⁻¹ or0.3-1.0 hr⁻¹. A gas may flow concurrently through the column with thecomposition. In certain embodiments, the gas is an inert gas (e.g.,nitrogen or argon), hydrogen, air, or oxygen. In other embodiments, thegas is a mixture of inert gas with hydrogen, air, oxygen, or acombination thereof.

In certain embodiments, at least a portion of the hydrocarbons producedby exposure to the catalyst are unsaturated hydrocarbons, and theunsaturated hydrocarbons are further hydrogenated to produce saturatedhydrocarbons. In some embodiments, the hydrocarbons produced by exposureto the catalyst are further fractionated to produce one or morehydrocarbon fractions.

In one embodiment, the hydrocarbons are utilized as a fuel in an engine.In another embodiment, the hydrocarbons are utilized as an aviationfuel. In yet another embodiment, the hydrocarbons are blended withpetroleum fuel to produce a blended fuel. In another embodiment, atleast a portion of the hydrocarbons are utilized as a reactant in achemical synthesis reaction.

Some embodiments of the disclosed catalysts, when exposed to acomposition comprising fatty acids, remain capable of deoxygenating atleast 10% of the fatty acids in the composition for at least 200 minutesat a temperature of 200-500° C. and a WHSV of 0.1-2.0 hr⁻¹. Certainembodiments of the catalysts remain capable of deoxygenation for atleast 15,000 minutes.

In some embodiments, exposing a composition comprising fatty acids to acatalyst comprising platinum and a non-transition metal on a supportdehydrogenates at least 10% of the fatty acids to produce a productcomprising branched, cyclic, and/or aromatic compounds. In certainembodiments, the catalyst also deoxygenates at least 10% of the product.In particular embodiments, at least 10% of the fatty acids in thecomposition are unsaturated fatty acids and transfer hydrogenationoccurs.

Embodiments of mixtures suitable for use as a renewable fuel aredisclosed. The mixtures are primarily comprised of hydrocarbons producedby fatty acid deoxygenation, primarily via decarboxylation. In someembodiments, the mixtures comprise greater than 70%, greater than 80%,or greater than 90% C15-C17 hydrocarbons.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of percent pentadecane yield versus percent palmiticacid conversion for various catalysts.

FIG. 2 is a graph of percent pentadecane yield versus percent palmiticacid conversion for various catalyst supports.

FIG. 3 is a graph of palmitic acid feedstock conversion versus percentplatinum loading for WO₃/Pt/ZrO₂ catalysts.

FIG. 4 is a graph of palmitic acid feedstock conversion versus percentWO₃ loading for WO₃/Pt/ZrO₂ catalysts.

FIG. 5 is a bar graph illustrating percent conversion, mass recovery,and products formed when palmitic acid was exposed to WO₃/Pt on variousZrO₂ supports.

FIG. 6 is a graph of pentadecane yield versus percent conversion whenpalmitic acid was exposed to WO₃/Pt on various ZrO₂ supports.

FIG. 7 is a bar graph illustrating percent conversion, mass recovery,and products formed when palmitic acid was exposed to variouscarbon-based catalysts.

FIG. 8 is a bar graph illustrating percent conversion, mass recovery,and products formed when oleic acid was exposed to various catalysts.

FIG. 9 is a bar graph illustrating the percent conversion, yield of C17hydrocarbons, and yield of stearic acid formed when oleic acid wasexposed to various carbon-based catalysts.

FIG. 10 is a gas chromatography trace of products formed when oleic acidwas exposed to one embodiment of the disclosed catalysts.

FIG. 11 is a mass spectroscopy fragmentation pattern of the peakobtained at 4.911 minutes in FIG. 10.

FIG. 12 is a mass spectroscopy fragmentation pattern of the peakobtained at 5.002 minutes in FIG. 10.

FIG. 13 is a mass spectroscopy fragmentation pattern of the peakobtained at 5.125 minutes in FIG. 10.

FIG. 14 is a mass spectroscopy fragmentation pattern of the peakobtained at 5.262 minutes in FIG. 10.

FIG. 15 is an overlay of GC-FID traces of products formed when palmiticacid and oleic acid were exposed to a Pt/Ge/C catalyst.

FIG. 16 is a bar graph illustrating products formed and mass balancerecovered when palmitic acid was exposed to one embodiment of thedisclosed catalysts under the conditions of Run 1 as described in theExamples.

FIG. 17 is a graph of percent conversion and percent decarboxylationversus time-on-stream for Run 1.

FIG. 18 is a bar graph illustrating products formed and mass balancerecovered when palmitic acid was exposed to one embodiment of thedisclosed catalysts under the conditions of Run 2 as described in theExamples.

FIG. 19 is a graph of percent conversion and percent decarboxylationversus time-on-stream for Run 2.

FIG. 20 is a bar graph illustrating products formed and mass balancerecovered when oleic acid, followed by palmitic acid, was exposed to oneembodiment of the disclosed catalysts under the conditions of Run 3 asdescribed in the Examples.

FIG. 21 is a graph of percent conversion and percent decarboxylationversus time-on-stream for Run 3.

FIG. 22 is a bar graph illustrating products formed and mass balancerecovered when palmitic acid was exposed to one embodiment of thedisclosed catalysts under the conditions of Run 4 as described in theExamples.

FIG. 23 is a graph of percent conversion and percent decarboxylationversus time-on-stream for Run 4.

FIG. 24 is a bar graph illustrating products formed and mass balancerecovered when oleic acid, followed by palmitic acid, was exposed to oneembodiment of the disclosed catalysts under the conditions of Run 5 asdescribed in the Examples.

FIG. 25 is a graph of percent conversion and percent decarboxylationversus time-on-stream for Run 5.

FIG. 26 is a bar graph illustrating products formed and mass balancerecovered when a mixture of oleic acid and palmitic acid, followed bypalmitic acid, was exposed to one embodiment of the disclosed catalystsunder the conditions of Run 6 as described in the Examples.

FIG. 27 is a graph of percent conversion of each fatty acid and overallpercent decarboxylation versus time-on-stream for Run 6.

FIGS. 28 a-b are a bar graph (FIG. 28 a) illustrating products formedand mass balance recovered when a mixture of stearic acid (SA) andpalmitic acid (PA) was exposed to one embodiment of the disclosedcatalysts under the conditions of Run 7 (FIG. 28 b) as described in theExamples.

FIG. 29 is a graph of percent material balance recovered and overallpercent decarboxylation versus time-on-stream for Run 7.

FIGS. 30 a-b are a bar graph (FIG. 30 a) illustrating products formedand mass balance recovered when oleic acid followed by a mixture oflinoleic acid and oleic acid was exposed to one embodiment of thedisclosed catalysts under the conditions of Run 8 (FIG. 30 b) asdescribed in the Examples.

FIG. 31 is a graph of percent material balance recovered and overallcombined percent decarboxylation and decarbonylation versustime-on-stream for Run 8.

DETAILED DESCRIPTION

Disclosed herein are embodiments of methods for making renewable fuel(such as renewable gasoline, renewable diesel, or renewable aviationfuel) by deoxygenating fatty acids via decarboxylation, decarbonylation,and/or dehydration to produce hydrocarbons. Also disclosed areembodiments of highly active, selective catalysts for deoxygenating freefatty acids. Catalytic deoxygenation of free fatty acids directlyproduces diesel-fraction hydrocarbons suitable for varioustransportation fuels, including but not limited to personal andindustrial diesel-powered devices such as cars, trucks, buses, trains,ferries, and airplanes. Renewable diesel has several advantages comparedto biodiesel. For example, oxygen-containing biodiesel is unsuitable foruse in aviation and typically is blended with petroleum diesel to beused in other applications. Renewable diesel produced by embodiments ofthe disclosed catalysts can be used without further modification orblending.

Embodiments of the disclosed catalysts are capable of deoxygenatingfatty acids to produce hydrocarbons in the absence of added hydrogen,thus allowing economical production of hydrocarbons at sites without areadily available source of hydrogen. Deoxygenation of unsaturated freefatty acids in the absence of added hydrogen also has the potential toproduce olefins of chemical value, such as building blocks for otherproducts of value.

I. TERMS AND DEFINITIONS

the following explanations of terms and abbreviations are provided tobetter describe the present disclosure and to guide those of ordinaryskill in the art in the practice of the present disclosure. As usedherein, “comprising” means “including” and the singular forms “a” or“an” or “the” include plural references unless the context clearlydictates otherwise. The term “or” refers to a single element of statedalternative elements or a combination of two or more elements, unlessthe context clearly indicates otherwise.

Unless explained otherwise, all technical and scientific terms usedherein have the same meaning as commonly understood to one of ordinaryskill in the art to which this disclosure belongs. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present disclosure, suitable methods andmaterials are described below. The materials, methods, and examples areillustrative only and not intended to be limiting. Other features of thedisclosure are apparent from the following detailed description and theclaims.

Unless otherwise indicated, all numbers expressing quantities ofcomponents, percentages, temperatures, times, and so forth, as used inthe specification or claims are to be understood as being modified bythe term “about.” Accordingly, unless otherwise indicated, implicitly orexplicitly, the numerical parameters set forth are approximations thatmay depend on the desired properties sought and/or limits of detectionunder standard test conditions/methods. When directly and explicitlydistinguishing embodiments from discussed prior art, the embodimentnumbers are not approximates unless the word “about” is recited.

Definitions of particular terms, not otherwise defined herein, may befound in Richard J. Lewis, Sr. (ed.), Hawley's Condensed ChemicalDictionary, published by John Wiley & Sons, Inc., 1997 (ISBN0-471-29205-2).

In order to facilitate review of the various embodiments of thedisclosure, the following explanations of specific terms are provided:

Catalyst: A substance, usually present in small amounts relative toreactants, that increases the rate of a chemical reaction without itselfbeing consumed or undergoing a chemical change. A catalyst also mayenable a reaction to proceed under different conditions (e.g., at alower temperature) than otherwise possible. Catalysts typically arehighly specific with respect to the reactions in which they participate.Some catalysts have a limited lifetime, after which they must bereplaced or regenerated. For example, reaction products or byproductsmay deposit on the catalyst's surface, reducing its activity.

Cetane number: A measurement of a diesel fuel composition's combustionquality during compression ignition. The cetane number is comparable tothe octane-number rating for gasoline. The higher the cetane number, themore easily the fuel can be ignited. The cetane number is the percentageof cetane (C₁₆H₃₄) that must be mixed with heptamethylnonane (cetanenumber=0) to give the same ignition performance under standardconditions as the fuel being rated.

Cloud point: The temperature at which a waxy solid material begins toappear as a diesel fuel is cooled, resulting in a cloudy appearance ofthe fuel. The presence of solidified waxes thickens the fuel and canclog fuel filters and fuel injectors. Wax also can accumulate on coldsurfaces.

Cracking: A refining process involving decomposition and molecularrecombination of long-chain hydrocarbons into shorter hydrocarbons.Thermal cracking exposes the hydrocarbons to temperatures of about500-950° C. for varying periods of time. Catalytic cracking occurs whenheated hydrocarbon vapors (about 400° C.) are passed over metal oxideand/or metallic catalysts (e.g., silica-alumina or platinum). Inhydrocracking, a catalyst is used and hydrogen is added to produceprimarily saturated hydrocarbons.

Decarboxylation: A chemical reaction in which carbon dioxide is removedfrom a chemical compound. For example, a fatty acid may bedecarboxylated to produce a hydrocarbon and carbon dioxide:R—COOH→R—H+CO₂.

Fatty acid: A carboxylic acid having a long, unbranched, aliphatic chainor tail. Naturally occurring fatty acids commonly contain from 4 to 28carbon atoms (usually an even number) including the carbon atom in thecarboxyl group. Free fatty acids can be represented by the generalformula RCOOH, where R is a saturated (i.e., all single bonds) orunsaturated (i.e., contains one or more double or triple bonds)aliphatic chain. Saturated fatty acids have only single bonds in thecarbon chain and can be described by the general formulaCH₃(CH₂)_(x)COOH. Unsaturated fatty acids have one or more double ortriple bonds in the carbon chain. Most natural fatty acids have analiphatic chain that has at least eight carbon atoms and an even numberof carbon atoms (including the carbon atom in the carboxyl group). Thefatty acid may be a liquid, semisolid, or solid. As used herein, theterm “fatty acids” refers to a composition comprising molecules, mono-,di-, and/or triglycerides of a single fatty acid, e.g., oleic acid, or acomposition comprising molecules, mono-, di-, and/or triglycerides of amixture of fatty acids, e.g., oleic acid and palmitic acid.

Olefin: An unsaturated aliphatic hydrocarbon having one or more doublebonds. Olefins with one double bond are alkenes; olefins with two doublebonds are alkadienes or diolefins. Olefins typically are obtained bycracking petroleum fractions at high temperatures (e.g., 800-950° C.).

Pore: One of many openings or void spaces in a solid substance of anykind. Pores are characterized by their diameters. According to IUPACnotation, micropores are small pores with diameters less than 2 nm. Amicroporous material has pores with a mean diameter of less than 2 nm.Mesopores are mid-sized pores with diameters from 2 nm to 50 nm. Amesoporous material has pores with a mean diameter from 2 nm and 50 nm.Macropores are large pores with diameters greater than 50 nm. Amacroporous material has pores with a mean diameter greater than 50 nm.

Porous: A term used to describe a matrix or material that is permeableto at least some fluids (such as liquids or gases). For example, aporous matrix is a matrix that is permeated by a network of pores(voids) that may be filled with a fluid. In some examples, both thematrix and the pore network (also known as the pore space) arecontinuous, so as to form two interpenetrating continua.

Pour point: The lowest temperature at which a liquid will pour or flowunder prescribed conditions.

Renewable diesel: Diesel-quality, non-FAME (fatty acid methyl ester)fuels derived from renewable resources that are suitable for use in mostordinary compression ignition engines. Renewable diesel is substantiallyoxygen-free and is a direct replacement for petroleum diesel.

Renewable fuel: Fuel (e.g., gasoline, diesel, aviation) derived fromrenewable resources, e.g., plant and/or animal resources.

TOS: Time-on-stream. As used herein, TOS is the length of time that thecatalyst has been converting feed to product.

Transfer hydrogenation: A reaction in which the hydrogen produced bydehydrogenating one molecule is transferred to a second molecule,thereby hydrogenating the second molecule.

WHSV: Weight hourly space velocity. As used herein, WHSV is the weightof feed flowing per weight of catalyst per hour.

II. CATALYSTS FOR CONVERSION OF FATTY ACIDS TO HYDROCARBONS

The disclosed catalysts are suitable for conversion of saturated and/orunsaturated fatty acids to hydrocarbon products. The disclosed catalystsare capable of deoxygenating saturated and/or unsaturated fatty acidsvia decarboxylation. In some embodiments, decarbonylation, alkylation,isomerization, cracking, hydrogenation/dehydrogenation, cyclization,and/or aromatization also occur. The hydrocarbon products are suitablefor use as a renewable fuel. Some fractions of the fuel may be suitablefor use as gasoline or aviation fuel.

Embodiments of the catalysts comprise a Group VIII metal, a supportmaterial, and a transition metal oxide or non-transition metal. Thesupport material is carbon, a metal oxide, or a metalloid oxide.Typically the support material is, at least in part, porous. In someembodiments where the support is a metal oxide or metalloid oxide, thecatalyst further includes a transition metal oxide. In other embodimentswhere the support is carbon, the catalyst further includes one or morenon-transition metals.

In some embodiments, the Group VIII metal is selected from Co, Ir, Ni,Pd, Pt, Ru, or a combination thereof. In particular embodiments, theGroup VIII metal is Pt. In some embodiments, the metal oxide ormetalloid oxide support is selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, or acombination thereof. In several working embodiments, the metal oxidesupport was TiO₂ or ZrO₂. In particular embodiments, the catalystincludes a Group VIII metal, a metal oxide or metalloid oxide support,and a transition metal oxide. In certain examples, the transition metaloxide is molybdenum (VI) oxide (MoO₃) or tungsten (VI) oxide (WO₃).Exemplary catalysts include Pt/Al₂O₃, Pt/TiO₂, Pt/ZrO₂, MoO₃/Pt/ZrO₂,and WO₃/Pt/ZrO₂.

When the support is carbon, the catalyst may include a Group VIII metaland also may include one or more additional metals, typically anon-transition metal (e.g., Ge, Sn, Pb, Bi). For example, the catalystmay include platinum and a non-transition metal such as germanium ortin. The non-transition metal in combination with the Group VIII metalincreases the activity of the catalyst compared to the Group VIII metalalone. Exemplary catalysts include Pt/Ge/C, Pt/Ru/C, and Pt/Sn/C. Inworking examples, surprisingly superior results were obtained withWO₃/Pt/ZrO₂, MoO₃/Pt/ZrO₂, Pt/TiO₂, Pt/Ge/C, and Pt/Sn/C.

For instance, as discussed in detail in Example 1, out of the more than100 catalyst samples screened, one composition, i.e., WO₃/Pt/ZrO₂,unexpectedly worked surprisingly well for deoxygenating saturated fattyacids via decarboxylation with up to 100% conversion. WO₃/Pt/ZrO₂ is anacidic catalyst. At the time of the invention, conventional thought wasthat acidic catalysts would be unsuitable for a continuous-flow processbecause of their tendency to build up surface coke deposits duringhydrocarbon processing, thereby losing activity. Sooknoi et al., forexample, investigated deoxygenation of methyl esters over zeolitecatalysts, including NaX, and stated that, typical of acid catalysts,rapid deactivation was observed with NaX and was probably due to cokeformation over the acid sites. (J. of Catalysis, 258 (2008) 199-209.)However, surprisingly, addition of platinum to tungstated zirconiaameliorated the problem of coke formation, allowing the catalyst toremain active for relatively long periods of time. In a workingembodiment, a WO₃/Pt/ZrO₂ catalyst was shown to produce 90-100% palmiticacid conversion for up to 800 minutes in a continuous-flow process. Inanother working embodiment, a WO₃/Pt/ZrO₂ catalyst was shown to still becapable of 60-90% palmitic acid conversion after 18,000 minutes (300hours) in a continuous-flow process.

Catalysts comprising platinum/germanium or platinum/tin on carbonsupports also were shown to produce unexpectedly superior results,particularly with respect to decarboxylating unsaturated fatty acids.Some Group VIII metals on carbon, e.g., 5 wt % Pd/C, are capable ofdecarboxylating saturated fatty acids. However, Pd/C has low activitywith unsaturated fatty acids, and exhibits poor stability when used in aliquid-phase continuous process. Additionally, double-bond rearrangementand side reactions such as cracking can hinder decarboxylation activity.An initial screening assay (Example 1) demonstrated that a Pt/Ge/Ccatalyst converted more than 95% of an oleic acid feed to heptadecane. APt/Sn/C catalyst converted more than 85% of the oleic acid feed toheptadecane. In contrast, a Pt/C catalyst converted less than 60% of theoleic acid feed to heptadecane. As described in Example 3, a workingembodiment of a Pt/Sn/C catalyst continued to deoxygenate about 60% ofan oleic acid feed for up to 500 hours in a liquid-phase,continuous-flow process.

The following exemplary catalyst compositions are not meant to be exactor limiting. Variations of the relative amounts of the components mayprovide a catalyst of similar performance, superior performance, orpoorer performance. Because platinum is expensive, however, it istypically advantageous to minimize the amount of platinum in thecatalyst. In some embodiments, the mass of platinum relative to the massof the catalyst is less than or equal to 5 wt %, less than 2 wt %, orless than 1 wt %. For example, the platinum may be present in an amountof 5 wt %, 1 wt % to 5 wt %, 0.4 wt % to 2 wt %, 0.5 wt % to 1.5 wt %,or 0.7 wt %. Typically, 1 wt % to 5 wt % platinum is used in conjunctionwith carbon-based supports.

Although platinum may be present in concentrations up to 5 wt % on metaloxide or metalloid oxide supports, smaller amounts (e.g., 0.5 wt % to1.5 wt %) can be used in conjunction with metal oxide-based supportssuch as ZrO₂ that further include a transition metal oxide such as MoO₃or WO₃. In some embodiments, the catalyst satisfies the formulaMO₃/Pt/ZrO₂. In certain embodiments, M is W, Mo, or a combinationthereof. The catalyst includes MO₃ and Pt in a relative weight ratioranging from 300:1 to 3:1, such as a weight ratio from 100:1 to 10:1, ora weight ratio from 20:1 to 10:1. For example, in some embodiments, thecatalyst comprises 0.1 wt % to 1.5 wt % Pt and 6 wt % to 30 wt % MO₃ onZrO₂, relative to the total mass of catalyst. In a working embodimentthat evaluated the effects of Pt and WO₃ concentration on palmitic acidconversion (primarily via decarboxylation) to hydrocarbon products, aWO₃/Pt/ZrO₂ catalyst having 12 wt % WO₃ and 0.7 wt % Pt on a ZrO₂support provided unexpected and superior results. In another workingembodiment, a catalyst having 7.8 wt % MoO₃ and 0.7 wt % Pt on a ZrO₂support also provided unexpected and superior results.

Embodiments of carbon-based catalysts include platinum and anon-transition metal in a relative weight ratio of 50:1 to 1:1, such asa weight ratio of 10:1 to 3:1. For example, the catalyst may include 1wt % to 5 wt % Pt or 1.5 wt % to 5 wt % Pt, relative to the mass ofcatalyst. In some embodiments, the mass of platinum is 1.5 wt %, 3 wt %,or 5 wt %. Disclosed embodiments of the carbon-based catalysts alsoinclude 0.1 wt % to 5 wt % Ge or Sn, relative to the mass of thecatalyst. Catalysts including 5 wt % Pt and 0.5-1 wt % Ge on carbon or1.5 wt % Pt/0.15 wt % Sn on carbon were found, unexpectedly, to beeffective catalysts for decarboxylating palmitic acid. Workingembodiments concerning oleic acid conversion to deoxygenated productdemonstrated unexpectedly superior results with Pt/Ge/C and Pt/Sn/Ccatalysts.

III. CATALYST SYNTHESIS

A. Platinum on Metal Oxide Support

Catalysts comprising platinum on a metal oxide support are disclosed.Zirconia supports may be prepared by calcining zirconia at 450-850° C.for 2-6 hours, e.g., at 450° C. for 2 hours. In some embodiments, thezirconia may include a binder, such as graphite or cornstarch. Incertain embodiments, the zirconia is ground and sieved prior tocalcination.

When preparing catalyst compositions including Pt and WO₃, WO₃ typicallyis added after calcination and before addition of Pt. For example, anaqueous tungsten solution (e.g., ammonium metatungstate hydrate) may beadded to the zirconia support by the incipient wetness technique.Incipient wetness impregnation is performed by dissolving a metal saltin an appropriate solvent, and then adding the solution to a porouscatalyst support. The amount of the solution added corresponds to thepore volume of the catalyst support. The concentration of solution isselected such that the desired mass of metal salt is added to thesupport. Capillary action draws the solution into the support's pores.The catalyst is then dried and/or calcined, depositing the metal salt onthe catalyst surface. In the disclosed working embodiments, an ammoniummetatungstate solution was added to the calcined zirconia support. Theimpregnated support was then dried and subsequently calcined.

Platinum is then added to the tungstated zirconia. In some embodiments,an aqueous platinum ethanolamine solution is added via the incipientwetness technique. The Pt-impregnated tungstated zirconia is then dried,calcined, and optionally ground and sieved.

In other embodiments, platinum is added by combining tungstated zirconiaand platinum acetylacetonate in a round-bottom flask, which is placed ona rotary evaporator and heated under vacuum. The WO₃/Pt/ZrO₂ catalystthen is calcined. In one working embodiment, the catalyst subsequentlywas reduced in a hydrogen atmosphere at 350° C.

Platinum acetylacetonate may be used as described above to add platinumto titania supports. The titania support optionally is calcined, e.g.,at 450-900° C. The titania support may be ground and sieved beforeadding platinum.

In some embodiments, MoO₃/Pt/ZrO₂ catalysts are prepared by firstcalcining a zirconia support, e.g., at 450° C. An aqueous solution ofammonium heptamolybdate hydrate is added by the incipient wetnesstechnique, followed by drying and calcination, e.g., at 850° C. Anaqueous solution of platinum ethanolamine subsequently is added by theincipient wetness technique, followed by drying and calcination.

In some embodiments, Pt/ZrO₂ catalysts are prepared by calcining azirconia support, and then adding Pt by the incipient wetness techniqueusing an aqueous solution of platinum ethanolamine, followed by dryingand calcination. The zirconia support may be ground and sieved first toprovide improved platinum dispersion on the zirconia surface. Platinumis added using platinum acetylacetonate, as described above. Aftercalcination, the catalyst may be reduced, such as in a hydrogenatmosphere at 350° C.

B. Platinum/Non-transition Metal on Carbon Support

The platinum/germanium and platinum/tin catalysts may be prepared viaseveral techniques known in the art. One such method uses the incipientwetness technique to add metals to a carbon support. Addition of the Ptand non-transition metal may be done simultaneously or sequentially. Forsimultaneous addition, a suitable Pt precursor (e.g., platinumethanolamine, chloroplatinic acid) and a suitable Ge or Sn precursorsuch as the chloride or oxide form are mixed with a sufficientconcentration of acid (e.g., HCl) to prevent precipitation and producean impregnation solution. The volume of the impregnation solution isthen adjusted with either acid or deionized water such that the volumeof the solution will fill pores of the carbon support and the metalsremain soluble. The impregnation solution is then added to the carbonsupport. The catalyst is dried. In some instances, the catalyst iscalcined and/or reduced prior to application.

Alternatively, the Pt and non-transition metal may be addedsequentially. A suitable Pt precursor (e.g., platinum ethanolamine,chloroplatinic acid) is first dissolved to make an impregnationsolution, and the volume is adjusted to fill the pore volume of thecarbon support using deionized water or other appropriate solvent, suchas an alcohol (e.g., methanol, ethanol) or a ketone (e.g., acetone,methyl-isobutyl ketone). The dissolved Pt solution is then slowly addedsuch that the incipient wetness point of the support is reached when thesolution is consumed. The Pt-impregnated support may then be dried,calcined and/or chemically reduced. Next, a suitable Sn or Ge precursor,such as a chloride or oxide precursor, is dissolved in a sufficientconcentration of acid or solvent (e.g., ethanol) to preventprecipitation. The solution volume is then adjusted with HCl, deionizedwater, or additional solvent such that upon addition of the solution tothe Pt-supported carbon the incipient wetness point is reached. Thecatalyst is then dried and can be calcined and/or reduced prior toapplication.

IV. FATTY ACID CONVERSION AND DEOXYGENATION BY DECARBOXYLATION AND/ORDECARBONYLATION

Naturally occurring fatty acids (i.e., animal fats and plant-basedoils/fats) typically are found in triglycerides, where three fatty acidsare esterified to a glycerol backbone

where R₁, R₂, and R₃ are unbranched aliphatic chains. R₁, R₂, and R₃ maybe the same or different from one another. For example, R₁, R₂, and R₃may be different in length from one another. Additionally, R₁, R₂, andR₃ may differ in the number and/or placement of any double and/or triplebonds.

Suitable fatty acid sources comprise plant-based oils, plant-based fats,animal fats, or any combination thereof. The terms “plant-based” oil or“plant-based” fat as used herein encompass oils or fats obtained fromany part of a plant, including the leaves, stems, roots, flowers, seeds,fruits, or any other part of the plant. In some embodiments, the fattyacid source comprises a plurality of plant-based oils, plant-based fats,animal fats, or any combination thereof.

In some embodiments, the fatty acids are separated from the glycerolbackbone by hydrolyzing the ester bonds to produce glycerol and freefatty acids having the generic formula RCOOH. Hydrolysis can beperformed by any suitable method known to one of ordinary skill in theart. The glycerol and free fatty acids are separated, and the free fattyacids are then deoxygenated. The recovered glycerol has significanteconomic value and can be used in other processes and formulations.Hydrolysis typically separates up to 100% of the fatty acids from theglycerol backbone. For example, hydrolysis may separate at least 10%, atleast 50%, at least 80%, or at least 95% of the fatty acids from theglycerol backbone.

In some embodiments, the fatty acids are hydrogenated to form saturatedfatty acids prior to deoxygenation. Hydrogenation may be performedbefore or after removal of the glycerol backbone. For example, soybeanoil, which typically includes about 80% unsaturated fatty acids, may behydrogenated by any suitable method known to one of ordinary skill inthe art prior to de-esterification and decarboxylation. Hydrogenationtypically saturates at least 10%, at least 50%, at least 80%, at least95%, or 100% of the double and/or triple bonds in a sample comprisingunsaturated fatty acids. In some embodiments, hydrogenation may be usedto improve the stability of the fatty acid feed for storage prior todeoxygenation. For example, soybean oil comprises a large amount oflinoleic acid, which can react with air, thereby turning the oil rancid.In some embodiments, the fatty acid feed may be pretreated by anysuitable method known to those skilled in the art to remove undesirablecompounds (e.g., phospholipids) before hydrolysis, hydrogenation, and/ordeoxygenation.

Contacting embodiments of the disclosed catalysts with fatty acidsresults in deoxygenation of at least some of the fatty acids viadecarboxylation. Decarboxylation of the fatty acids removes CO₂,producing a hydrocarbon. In the case of palmitic acid, a saturated fattyacid having 16 carbons, decarboxylation produces pentadecane:

Although triglycerides are usually hydrolyzed prior to deoxygenation sothat the glycerol can be recovered, triglycerides may be deoxygenatedwith embodiments of the disclosed catalysts. However, triglyceridedeoxygenation typically decomposes and gasifies a substantial portion ofthe glycerol backbone, thereby eliminating economic benefits associatedwith recovery and subsequent use of glycerol. Other esters of fattyacids also may be processed with certain embodiments of the disclosedcatalysts to provide hydrocarbon products.

Embodiments of the disclosed catalysts deoxygenate, via decarboxylation,from 10% to 100% of the fatty acids when a composition comprising fattyacids is exposed to the catalysts. The catalyst may provide additionaldeoxygenation via decarbonylation and dehydration. In some embodiments,the disclosed catalysts are capable of deoxygenating at least 10%, atleast 20%, at least 25%, at least 50%, at least 75%, at least 80%, atleast 90%, or at least 95% of the fatty acids in a fatty acidcomposition. For example, the disclosed catalysts may deoxygenate20-80%, 50-80%, 60-95%, or 80-100% of the fatty acids. The fatty acidcomposition may consist essentially of fatty acids, or may comprisefatty acids diluted in a suitable solvent (e.g., a liquid hydrocarbonsolvent). The fatty acids may be free fatty acids, fatty acid esters,fatty acid monoglycerides, fatty acid diglycerides, fatty acidtriglycerides, or any combination thereof in any ratio. In particularembodiments, up to 100% of the fatty acids are free fatty acids. Forexample, at least 10%, at least 50%, at least 80%, or at least 95% ofthe fatty acids are free fatty acids.

Deoxygenation can be performed as a batch process, in which a catalystand fatty acids are combined (e.g., in a slurry) and allowed to reactfor a period of time. Typically fatty acids are used without dilution.However, the fatty acids may be diluted with a solvent, particularly ifthe fatty acids are waxy or in solid form. Suitable solvents includehydrocarbon solvents, particularly liquid hydrocarbon solvents. Incertain embodiments, the hydrocarbon solvent is recycled hydrocarbonsproduced by decarboxylation of fatty acids.

In some examples, the reaction time is 2-6 hours. In one workingembodiment, the reaction time was 4 hours. The reaction mixture may beheated to a temperature of 200-500° C., such as 250-350° C. Optionally,the slurry is mixed continuously or periodically throughout the reactiontime by suitable means such as mechanical stirring or shaking.

In other embodiments, deoxygenation is a continuous or substantiallycontinuous process in which a fatty acid feed flows across or through acatalyst bed. For example, a column containing a packed catalyst bed isprepared, and a fatty acid feed is flowed through the column. The fattyacids may be free fatty acids, or they may be in the form oftriglycerides, fatty acid esters, or mixtures thereof. Typically thefatty acids are used without dilution. However, in some instances (e.g.,if the fatty acids are a wax or solid) the fatty acids may be dilutedwith a hydrocarbon solvent, particularly a hydrocarbon solvent that is aliquid at ambient temperature. In certain embodiments, the hydrocarbonsolvent is recycled hydrocarbons produced by deoxygenating fatty acidswith an embodiment of the disclosed catalysts.

Thus, deoxygenation is performed in mixtures comprising a plurality ofcatalyst particles having a first composition selected from a) Pt, MO₃,and ZrO₂, where M is W, Mo, or a combination thereof, b) Pt, Ge and C,c) Pt, Sn, and C, or d) any combination thereof, with a secondcomposition comprising fatty acids, wherein the second composition isput into fluid contact with the first composition.

The second composition may comprise triglycerides (e.g., in the form ofplant-based oils/fats or animal fats) or free fatty acids. In someembodiments, free fatty acids are obtained by hydrolyzing triglyceridesto produce free fatty acids and glycerol. In certain embodiments, thefree fatty acids and glycerol are at least partially separated, and atleast a portion of the glycerol is removed prior to putting the secondcomposition into contact with the first composition.

In some embodiments, the mixture further comprises hydrocarbons. In oneembodiment, the hydrocarbons are formed when the second composition isput into contact with the first composition. In another embodiment, thesecond composition comprises a mixture of fatty acids and a hydrocarbonsolvent. In one embodiment, the hydrocarbon solvent is obtained byrecycling hydrocarbons formed by deoxygenating fatty acids with anembodiment of the disclosed catalysts.

In some embodiments, deoxygenation is performed using an up-flow column.The fatty acid feed flows into the bottom of the column, and thedecarboxylated hydrocarbons and CO₂ flow out the top of the column.Typically the column is heated to a temperature of 200-500° C., such as250-350° C. In some embodiments, the fatty acid feed also is preheatedbefore flowing into the column. For example, if the fatty acid feed is awax or solid at ambient temperature, it may be heated to form a liquid.The fatty acids may be preheated to at least 50° C., at least 100° C.,70-350° C., 100-350° C., or to the operating temperature of the column,e.g., 200-500° C. or 250-350° C.

In other embodiments, the fatty acid feed is not preheated and isintroduced into the column at ambient temperature. Unsaturated fattyacids inherently are more reactive than saturated fatty acids, and mayundergo at least some dimerization and/or oligomerization if preheatedbefore exposure to the catalyst. As the temperature increases, morecracking occurs, producing more light hydrocarbons (e.g., C1-C4hydrocarbons) and increasing product heterogeneity.

A person of ordinary skill in the art will appreciate that fatty acidflow rates through the column are determined based upon a number ofvariables including, but not limited to, catalyst composition, columndimensions, temperature, fatty acid feed composition, and combinationsthereof. In some examples, the flow rate has a weight hourly spacevelocity (WHSV) of 0.1-2.0 hr⁻¹ or 0.3-1.0 hr⁻¹. In some embodiments,flow rates near the lower end of the WHSV range increase fatty acidconversion, catalyst lifetime, and/or product distribution orheterogeneity. For example, increasing the catalyst contact time (e.g.,by decreasing WHSV) may increase the amount of cracking, rearrangement,and/or cyclization of the product hydrocarbons. The broader productdistribution can lower the cloud point and/or freezing point of theproduct, and may make the product more suitable for aviation use. Inseveral working embodiments, the WHSV was 0.3-0.4 hr⁻¹.

In some embodiments, the column is purged with an inert gas, e.g., N₂,before starting the fatty acid feed. In other embodiments, the columnmay be purged with air or a gas including some oxygen. Oxygen acts as ahydrogen scavenger and can remove hydrogen associated with the catalystsurface, thereby increasing the catalyst activity for reactionsinvolving dehydrogenation. In some embodiments, the catalyst is purgedwith oxygen at a lower temperature (e.g., 50-150° C.) before or whilebeing contacted with the fatty acids to promote dehydrogenation; thefatty acids are later contacted with the same or another catalyst attypical operating temperatures of 200-500° C. Purging with an inert gasalso can remove at least some hydrogen associated with the catalystsurface via diffusion.

The disclosed catalysts demonstrate deoxygenation (typicallydecarboxylation) activity in the absence of added hydrogen and/or highpressure. For example, the disclosed catalysts can be used at anydesired operating temperature at pressures ranging from ambient pressureto less than 250 psi. In some embodiments, the catalysts are used atpressures less than 100 psi. In certain systems, the columns areoperated at pressure of 80 psi to facilitate mechanical operation suchas maintaining pump operation and sealed valves. In contrast, currentcommercially available decarboxylation catalysts typically requirehydrogen to maintain catalytic activity and are used in a 3-phasesystem: solid catalyst, liquid fatty acid feed, and gaseous hydrogen.Because the catalyst is coated with the liquid fatty acid feed, hydrogenmust be solubilized in the liquid to reach the catalyst surface.Solubilization is attained by operating the system under high pressure,e.g., 2,000 psi. The disclosed catalysts' ability to performdeoxygenation via decarboxylation without added hydrogen enablesdeoxygenation plants to be located near a fatty acid source without alsobeing located near a hydrogen source. Furthermore, operating at lowerpressures enables less expensive process equipment such as lowerpressure pumps, lower pressure valves and piping, and lowerpressure-rated catalyst columns to be used, thereby reducing the cost ofbuilding the deoxygenation system and providing economic viability for acommercial scale operation

Additionally, certain embodiments of the disclosed catalysts are wellsuited for use in continuous, liquid-flow systems and remain capable ofdeoxygenating at least 10% of the fatty acids in a fatty acid feed forat least 200 minutes at temperatures of 200-500° C. and WHSV of 0.1-2.0hr⁻¹. Under such conditions, certain working embodiments of thedisclosed catalysts decarboxylated at least 80% of the fatty acids in afatty acid feed for at least 400 minutes or at least 700 minutes. Someembodiments of the disclosed catalysts demonstrate deoxygenationactivity for more than 350 hours. In working embodiments, deoxygenationactivity was demonstrated for at least 300 minutes, at least 500minutes, at least 800 minutes, at least 1,000 minutes, or at least20,000 minutes. In one working embodiment, the percent deoxygenationafter 22,000 minutes (367 hours) was substantially the same as theinitial percent deoxygenation.

Certain embodiments of the disclosed catalysts produce at least someisomerization during deoxygenation, resulting in methyl-branchedhydrocarbons. For example, deoxygenation of palmitic acid may alsoproduce 2-, 3-, 4-, or 5-methyltetradecane along with pentadecane. Themethyl group may be located at any position along the carbon chain. Thepresence of methyl-branched hydrocarbons in renewable diesel can beadvantageous by lowering the cloud point and pour point of the fuel. Themethyl group reduces the ability of the fuel to solidify and/or becomewaxy by disrupting the “stacking” of adjacent saturated hydrocarbons.

Although a single methyl group is beneficial, additional branchingreduces the cetane value of the fuel. Catalyst compositions includingWO₃/Pt/ZrO₂ were unexpectedly found to provide surprisingly superiorresults with respect to producing mono-methyl-branched hydrocarbons.Little-to-no methyl branching was seen with catalyst embodimentscomprising Pt/Ge or Pt/Sn on carbon.

While WO₃/Pt/ZrO₂ was surprisingly found to provide excellent results asa catalyst for deoxygenating saturated fatty acids, it was found toalkylate unsaturated fatty acids, making it less suitable as a catalystfor feeds including a substantial percentage of unsaturated fatty acids.For example, alkylation occurred when oleic acid was exposed toWO₃/Pt/ZrO₂ catalysts. In one embodiment, up to 60-70% of the productswere alkylated, forming heavy, non-distillable products. Such alkylatedcompounds are too heavy to be useful as renewable diesel, makingalkylation an undesirable reaction when preparing renewable diesel.Thus, MO₃/Pt/ZrO₂ (M=W, Mo, or a combination thereof) catalysts aresuitable catalysts for fatty acid feeds including less than 50 wt %unsaturated fatty acids. For example, MO₃/Pt/ZrO₂ catalysts are selectedwhen the fatty acid feed contains at least 50 wt %, at least 75 wt %, orat least 95 wt % saturated fatty acids. Alternatively, a fatty acid feedincluding a substantial amount (e.g., greater than 50 wt %) ofunsaturated acids can be hydrogenated and subsequently deoxygenated witha MO₃/Pt/ZrO₂ catalyst.

Embodiments of the disclosed carbon-based catalysts, such as Pt/Ge orPt/Sn on carbon, provide unexpectedly superior results for deoxygenationof fatty acid feeds including a substantial amount of unsaturated fattyacids. These carbon supports are non-acidic and do not promote extensivealkylation and/or oligomerization reactions. Thus, they can be utilizedto deoxygenate unsaturated fatty acids such as oleic acid and linoleicacid. Pt/Ge and/or Pt/Sn on carbon catalysts are suitable catalysts forfatty acid feeds including at least 1 wt %, at least 50 wt %, at least80 wt %, or at least 99 wt % unsaturated fatty acids.

In some embodiments, the disclosed catalysts partially dehydrogenatefree fatty acids in a sample, resulting in subsequent branching,cyclization and/or aromatization. Cyclization and/or aromatization canenhance the products' suitability for use in fuels by lowering the cloudpoint and pour point of the fuel. Concomitantly, the released hydrogenmay react with other unsaturated fatty acids in the mixture, producingsaturated hydrocarbons. Additionally, rearrangements may occur in whichthe double bond is moved to a different position along the carbon chain.For example, the double bond in oleic acid may be moved from the omega-9position (i.e., ninth bond from the end of the carbon chain) to thealpha, or first, position or any other position along the hydrocarbonchain. Branching, cyclization and/or aromatization can result inproducts suitable for aviation fuels. The aviation fuel JP-8, forexample, typically contains 29% isoparaffins (i.e., branched-chainhydrocarbons), 20% cycloparaffins and 20% aromatics.

Dehydrogenation and cyclization/aromatization reactions can occur withembodiments of the disclosed catalysts. For instance, certainembodiments of the disclosed catalysts dehydrogenate and aromatize aportion of the molecules in a fatty acid feed, producing aromaticcompounds such as alkylated benzenes. These compounds may have highvalue, e.g., as surfactants. Although these reactions occur with bothtypes of catalysts and all feeds, they are more prevalent withembodiments of the disclosed carbon-based catalysts, i.e., Pt/Ge orPt/Sn on carbon and feed containing unsaturated fatty acids. Whilearomatic compounds (e.g., alkylated benzenes) are the predominant cyclicproduct, non-aromatic rings of other sizes also may be formed,particularly when MO₃/Pt/ZrO₂ catalysts are used. Without being bound byany particular theory, it is believed that a first dehydrogenation eventmay cyclize a fatty acid chain and produce, e.g., a 6-membered ring withrelease of a hydrogen molecule. With an unsaturated fatty acid, aninternal alkylation can occur producing a ring compound. The 6-memberedring can further dehydrogenate to form an aromatic ring with release ofan additional three H₂ molecules. The released hydrogen is transferredto and reacts with unsaturated fatty acid molecules in the feed (i.e.,transfer hydrogenation), forming saturated fatty acids, whichdeoxygenate to hydrocarbons. Transfer hydrogenation reduces theincidence of alkylation and/or oligomerization reactions betweenadjacent unsaturated fatty acid molecules. Additionally, the releasedhydrogen maintains the catalyst in a reduced state. Thus, certainembodiments of the disclosed catalysts result in both deoxygenation andtransfer hydrogenation of fatty acid molecules, producing deoxygenatedhydrocarbons, a portion of which are cyclic and/or aromatic, whileminimizing undesirable dimerization and/or oligomerization reactions. Inone embodiment, when the fatty acid feed was oleic acid, more than 90%of the resulting hydrocarbons were saturated, with heptadecane being themajor product.

Dehydrogenation can be increased by maintaining a hydrogen-starvedsystem. Operating in a hydrogen-starved atmosphere is advantageous whenproduction of unsaturated hydrocarbons is desirable. In addition tohaving utility as a fuel, the unsaturated hydrocarbons may be useful asstarting reactants for further conversions and chemical syntheses. Thus,in certain embodiments, deoxygenation is performed in a hydrogen-free,or hydrogen-deficient, atmosphere. A hydrogen-deficient atmosphere canbe facilitated by flowing an inert, non-hydrogen gas (e.g., N₂, Ar)through the column with the fatty acid feed. The gas facilitates removalof hydrogen via diffusion as some hydrogen diffuses from the catalystsurface to the gas. Alternatively, a hydrogen scavenger can be used toincrease the yield of alkyl-branched aromatics. When the fatty acid feedincludes a substantial percentage of unsaturated fatty acids, the feeditself acts as a hydrogen scavenger. In some embodiments, hydrogenproduced by dehydrogenating one fatty acid molecule is transferred to anearby unsaturated fatty acid molecule, i.e., transfer hydrogenation.Transfer hydrogenation reduces concomitant dimerization and/oroligomerization of the fatty acids, which can occur in the absence oftransfer hydrogenation. Oxygen can also be used as a hydrogen scavenger.Flowing air or a gas including oxygen (e.g., 1% to 100%) through thecolumn will facilitate maintaining a hydrogen-deficient atmosphere.

In some embodiments, a fatty acid feed is heated in the presence ofcatalyst at a temperature of at least 50° C. to facilitatedehydrogenation and subsequent deoxygenating is performed at atemperature of at least 250° C. These processes can be performed using asingle catalyst bed or column having different temperature zones, e.g.,a first temperature zone of at least 50° C. and a second temperaturezone of at least 250° C. In one embodiment, dehydrogenation is performedin a first catalyst bed at a temperature of at least 50° C. anddeoxygenation is performed in a second catalyst bed at a temperature ofat least 250° C. Catalyst in the first and second catalyst beds may havesubstantially the same chemical composition, e.g., 0.7 wt % Pt/12 wt %WO₃/ZrO₂. Alternatively, the two catalyst beds may contain catalystswith different compositions, i.e., different ratios of components ordifferent chemical compositions. For example, the first catalyst bed mayhave a Pt/Ge/C catalyst, and the second catalyst bed may have aPt/MO₃/ZrO₂ catalyst. In one embodiment, the first and second catalystbeds are in separate columns, which may be operated under the same ordifferent conditions (e.g., temperature, WHSV, purge gas, etc.). Inanother embodiment, the two catalyst beds are within a single columnsuch that, for example, a first zone within the column contains thefirst catalyst bed and a second zone within the column contains thesecond catalyst bed. The zones may be at the same or differenttemperatures.

In one embodiment, exposing a fatty acid feed to aplatinum/non-transition metal catalyst (e.g., Pt/Ge/C or Pt/Sn/C)dehydrogenates at least 10% of the fatty acids to produce branched,cyclic, and/or aromatic compounds. In another embodiment, theplatinum/non-transition metal catalyst also deoxygenates at least 10% ofthe fatty acids.

In some embodiments, the hydrocarbons produced by exposure to thecatalyst are subjected to one or more additional processes to stabilizethe fuel and/or improve the yield of a specific, desired fuel fraction.For example, in certain embodiments, at least a portion of thehydrocarbons produced by exposure to the catalyst are unsaturatedhydrocarbons, and the unsaturated hydrocarbons are further hydrogenatedto produce saturated hydrocarbons. Increased saturation may improve fuelstability for storage; at least some unsaturated hydrocarbons can reactwith air, thereby degrading the fuel quality.

Following deoxygenation, a preliminary product can be recovered. In someembodiments, the preliminary product is further processed. For example,the preliminary product may be fractionated, such as by fractionaldistillation or other suitable means, to produce one or more hydrocarbonfractions. The hydrocarbon fractions are free of trace metals.

In some embodiments, the preliminary product is a mixture comprisinghydrocarbons in a liquid state and trace amounts of Pt, W, Mo, and/orZr. In one embodiment, the mixture comprises a) hydrocarbons in a liquidstate and b) at least one part per million (ppm) Pt, at least 1 ppm W,Mo, or a combination thereof, and/or at least 1 ppm Zr. In anotherembodiment, the mixture comprises a) hydrocarbons in a liquid state andb) at least 1 ppm Pt, at least 10 ppm W, Mo, or a combination thereof,and/or at least 10 ppm Zr. In another embodiment, the mixture comprisesa) hydrocarbons in a liquid state and b) at least 1 ppm Pt, at least 10ppm W, Mo, or a combination thereof, and/or at least 50 ppm Zr.

In other embodiments, the preliminary product is a mixture comprisinghydrocarbons in a liquid state and Pt, Ge, and/or Sn. In one embodiment,the mixtures comprise a) hydrocarbons in a liquid state and b) at least1 ppm Pt and/or at least 0.5 ppm Ge and/or at least 0.5 ppm Sn. Forexample, a mixture may include a) liquid hydrocarbons, b) at least 1 ppmPt, and c) at least 1 ppm Ge or at least 1 ppm Sn or at least 1 ppm of acombination of Ge and Sn. In another embodiment, the mixtures comprisea) hydrocarbons in a liquid state and b) at least 5 ppm Pt and/or atleast 0.5 ppm Ge and/or at least 0.5 ppm Sn.

Embodiments of the disclosed catalysts and methods for using thecatalysts produce compositions and mixtures suitable for use as arenewable diesel fuel. The compositions and mixtures are primarilycomprised of hydrocarbons produced by fatty acid deoxygenation,primarily via decarboxylation. In some embodiments, the mixturescomprise greater than 70%, greater than 80%, or greater than 90% C15-C17hydrocarbons.

V. EXAMPLES Example 1 High-Throughput Catalyst Screening

Catalyst Preparation Most of the catalysts tested in the high throughputscreening were commercially available or prepared as described below.All extrudate or engineered-form catalysts were ground to a 30-100 meshsize before screening. Powder catalysts were used as obtained.

A few catalysts were prepared using high-throughput robotics forscreening purposes. These catalysts were WO₃/Pt on ZrO₂ supports, andwere prepared by incipient wetness impregnation. The ZrO₂ supports werecalcined at 450° C. for 6 hours and sized to 30-80 mesh. The supportswere added to quartz vials and placed on a vertical shaker on a liquidhandling robot. The vertical shaker allowed the supports to be agitatedduring impregnation. Metal impregnation of the supports was a two stepprocess. Bulk aqueous solutions of ammonium metatungstate hydrate andplatinum ethanolamine (Pt-A) were prepared and placed on a liquidhandling robot. Two sets of metal solution were then roboticallyprepared from these bulk solutions. The first set was a range oftungsten solutions, the second a range of platinum solutions. Thetungsten solutions were added first to the supports, drop-wise, whileagitating the solids. Once the supports were dried, agitation wasstopped. The supports were transferred to a furnace and calcined at 850°C. for 2 hours in air. The second impregnation was done with theplatinum solutions. Once dried, the supports were calcined at 450° C.for 2 h in air. The finished catalysts were tested as described in thegeneral high throughput screening procedure.

Catalyst Screening: High throughput catalyst screening for thedecarboxylation of free fatty acids was conducted using ahigh-temperature batch 24-well reactor made by Symyx. The 24 vials wereloaded with catalyst and free fatty acid feedstock, in a 2 to 1 weightratio. The vials were sealed under a nitrogen atmosphere with aKapton®-backed graphite sheet. Once loaded into the high temperaturereactor and sealed, the reactor headspace was pressurized with 40 psignitrogen to discourage leaking of the individual vials. The reactor wasplaced into a stationary furnace and heated to 300° C. for 4 hours.After completion the reactor was removed from the furnace and allowed tocool to room temperature.

Analytical work-up of each sample involved BSTFA/pyridinederivatization, which was carried out as follows. The sample was dilutedwith chloroform containing 1 mg/mL heptadecanoic acid as an internalstandard, mixed well, and centrifuged. A 500 μL aliquot was removed andadded to a 2 mL vial. To this second vial was added 500 μL ofN,O-bis[trimethylsilyl]trifluoroacetamide (BSTFA) and 500 μL ofpyridine. The vial was mixed well, capped, and heated to 70° C. for 1hour. GC-FID and GC-MS were utilized for quantification andidentification of the product mixture. Analysis was performed using aDB5-HT column (15 m×250 μm×0.10 μm nominal film thickness). The injectorwas held at 340° C. with a 150:1 split. With a flow rate of 2 mL/min H₂,the column was heated from 80° C. to 350° C. at 25° C./min and then heldat 350° C. for 9.2 min.

Effect of Metals on Palmitic Acid Decarboxylation: The catalysts shownin Table 1 were screened to determine the effect of various metals onpalmitic acid deoxygenation via decarboxylation. Some of the catalystcompositions yielded more symmetrical ketone dimers,CH₃—(CH₂)₁₄—C═O—(CH₂)₁₄—CH₃, via deoxygenation than hydrocarbon product.In general the catalysts giving symmetrical ketone dimers were of abasic metal oxide nature such as manganese dioxide. The ketone wouldrequire additional deoxygenation/cracking to provide hydrocarbonproduct.

Due to the screening nature of these tests and use of high throughputtechnology, mass recovery data are provided as an indication of thepotential integrity of the sample during testing. A low mass recovery isindicative of an individual vial leak, and data may not be of equalquality to data with high mass recovery since the more volatilecomponents, generally the hydrocarbon product, would be more prone tovaporization and leaking from the individual vial. The results aredepicted graphically in FIG. 1. In general, superior results wereobtained when catalysts contained platinum metal.

Included in the testing of more than 100 catalyst samples were someWO₃/Pt/ZrO₂ catalysts. These catalysts were initially thought to likelybe unsuitable for decarboxylation because they are acid catalysts, andacid catalysts have been reported to build up coke deposits duringhydrocarbon processing and lose activity. Nonetheless, WO₃/Pt/ZrO₂catalysts were included in the high-throughput screening simply becausethey were available. Surprisingly, the WO₃/Pt/ZrO₂ catalysts showed anunexpectedly high conversion percentage compared to either Pt/ZrO₂, orWO₃/ZrO₂ catalysts. As shown in Table 1, Pt/ZrO₂ catalysts producedconversions of 28-60%. A WO₃/ZrO₂ catalyst produced only 44% conversion.However, the WO₃/Pt/ZrO₂ catalysts produced 68-100% conversion. It isbelieved that the presence of Pt may make the catalyst “self-cleaning,”which aids in maintaining activity.

TABLE 1 Composition Mass Pentadecane Ketone Others Catalyst DetailsRecovery Conversion Yield Yield Yield 1 Pt/Ge/C 5% Pt/Ge on 61.0 100.0107.5 0.0 3.4 carbon powder 2 Pt/C * 48.9 83.2 33.4 0.0 9.4 3 Pt/Sn/C1.5% Pt/0.15% Sn 57.7 85.7 31.1 0.3 6.9 on carbon powder 4 Pt/C 5% Pt onNorit ROX 46.3 100.0 16.3 0.0 3.1 acid-washed carbon 5 Pt/Ru/C 1.5%Pt/0.15% Ru 83.8 58.6 15.8 0.2 10.6 on carbon powder 6 Pt(S)/C 3% Pt(sulphited) 76.5 26.8 1.1 0.0 8.4 on carbon powder 7 Pt/Al2O3 2% Pt onAl2O3 80.4 70.2 29.5 3.7 7.8 8 Pt/ZrO2 5% Pt on ZrO2 93.4 59.8 51.8 0.30.5 9 Pt/TiO2 5% Pt on TiO2 78.9 99.5 82.7 0.0 16.3 10 Pt/Al2O3 5% Pt onAl2O3 90.6 93.8 63.1 0.4 4.3 11 WO3/Pt/ZrO2 12% WO3/ 90.0 88.8 54.4 0.927.9 0.7% Pt on ZrO2 12 WO3/Pt/ZrO2 12% WO3/ 64.6 97.2 35.1 0.2 17.60.7% Pt on ZrO2 13 Pt/ZrO2 0.7% Pt on ZrO2 93.5 30.6 16.9 0.2 7.1 14Pt/ZrO2 0.7% Pt on ZrO2 92.8 29.7 15.5 0.4 11.5 15 Pt/ZrO2 0.7% Pt onZrO2 92.5 29.4 16.3 0.4 7.5 16 Pt/ZrO2 0.7% Pt on ZrO2 93.3 28.4 12.01.1 12.8 17 MoO3/Pt/ZrO2 7.8% MoO3/ 88.7 57.8 34.6 0.5 10.6 0.7% Pt onZrO2 18 MoO3/Pt/ZrO2 7.8% MoO3/ 92.4 42.0 21.7 1.6 4.3 0.7% Pt on ZrO219 WO3/Pt/ZrO2 12% WO3/ 70.7 99.6 42.1 0.2 10.8 0.7% Pt on ZrO2 20WO3/Pt/ZrO2 12% WO3/ 82.0 93.0 37.8 0.5 11.4 0.7% Pt on ZrO2 21 Pt/ZrO20.7% Pt on ZrO2 81.8 36.4 0.0 0.3 7.9 22 WO3/Pt/ZrO2 12% WO3/ 64.0 100.027.8 0.0 8.4 0.7% Pt on ZrO2 23 WO3/Pt/ZrO2 12% WO3/ 78.4 100.0 41.7 0.013.5 0.7% Pt on ZrO2 24 WO3/Pt/ZrO2 12% WO3/ 70.6 92.6 25.1 0.0 8.9 0.7%Pt on ZrO2 25 WO3/Pt/ZrO2 12% WO3/ 82.6 82.5 32.6 0.0 13.0 0.7% Pt onZrO2 by MVD 26 Pt/TiO2 0.7% Pt on TiO2 93.1 13.7 0.0 0.0 0.2 (900 C.calcine) 27 Pt/TiO2 0.7% Pt on TiO2 72.1 68.1 0.0 7.7 8.0 (450 C.calcine) 28 Pt/TiO2 0.7% Pt on TiO2 79.8 72.5 15.0 0.0 13.5 (uncalcined)29 WO3/Pt/ZrO2 12% WO3/ 75.3 100.0 56.0 0.2 28.8 0.7% Pt on ZrO2 30WO3/Pt/ZrO2 12% WO3/ 81.8 98.4 44.7 0.3 31.7 0.7% Pt on ZrO2 31WO3/Pt/ZrO2 12% WO3/ 78.6 100.0 43.0 0.7% Pt on ZrO2 32 WO3/Pt/ZrO2 12%WO3/ 78.0 68.3 37.5 0.2 21.7 0.7% Pt on ZrO2 33 WO3/Pt/ZrO2 12% WO3/65.6 100.0 32.8 0.0 10.8 0.7% Pt on ZrO2 34 WO3/Pt/ZrO2 12% WO3/ 62.5100.0 20.4 0.7% Pt on ZrO2 35 Pt/Al2O3 3% Pt on Al2O3 81.9 72.4 2.3 4.45.0 36 Pt/Al2O3 3% Pt on Al2O3 83.0 82.6 0.3 2.2 2.7 37 Pt/Al2O3 2% Pton Al2O3 56.9 86.3 10.6 1.8 4.3 38 Re/X5327 C Re on Engelhard 88.2 78.952.3 3.7 11.9 X5327 C 39 Escat 140 5.0% Pd on carbon 69.7 78.2 47.6 0.06.8 40 Re/C 5% Re on Engelhard 84.8 63.4 26.7 5.2 8.4 X5327 41 Ru/Ni78.6 88.9 23.1 3.3 8.4 42 G-69B 50% Ni on SiO2 77.0 80.7 12.0 1.5 10.643 Ni/Al2O3 91.0 63.9 11.8 1.3 7.4 44 Ni/Al2O3 46% Ni on Al2O3 85.3 85.88.4 2.7 6.1 45 Cu/Ni 1% Cu on 86.2 85.2 7.7 2.2 10.4 BASF G1-80 Ni 46Pd/Al2O3 97.2 28.2 4.4 3.3 2.9 47 Ru/Ni 1% Ru on 81.7 94.8 4.4 1.1 4.5BASF G1-80 Ni 48 Ni/SiO2 55% Ni on SiO2 70.0 93.3 4.3 0.7 6.7 49 Ru/TiO294.6 36.5 3.8 6.5 4.8 50 Co-1079 Co on SiO2 90.9 95.0 2.4 6.7 7.7 51Ni/C 5% Ni on Norit ROX 87.3 42.0 2.1 0.0 7.5 52 Pd/C 0.5% Pd on carbon93.4 26.6 1.4 0.0 3.2 (Englehard) 53 MnO2 86.2 100.0 0.0 6.9 3.510200-133-3 54 CaO 99.2 100.0 0.0 0.0 0.0 55 Co-0127 33% Co onKeiselguhr 90.1 100.0 0.0 8.3 2.9 56 Co-0138 93.8 100.0 0.0 1.0 0.5 57G-9 Cu/Mn 89.6 100.0 0.0 5.8 0.8 58 C61-1 CuO/ZnO 94.1 100.0 0.0 0.0 0.559 Ag2O/MnO2 91.1 99.6 0.0 16.8 4.6 60 Co-0138 96.1 99.3 0.0 7.3 1.7 61MnO2 - activated 83.8 98.8 0.0 38.4 6.5 62 γ-MnO2 88.6 98.4 0.0 44.5 6.563 Co-Re/Al2O3 Co/Re on Al2O3 85.6 95.0 0.0 5.2 17.9 64 Co-Re/Al2O3 96.093.4 0.0 3.4 1.4 65 Pentasil Sud-Chemie zeolite 66.3 91.8 0.0 0.2 5.1 66G-62 33-45% CoO/SiO2 89.6 88.0 0.0 4.1 10.4 67 Proc. Mont- 79.4 88.0 0.01.0 0.9 morillonite 68 1% Cu/Ni 93.3 86.1 0.0 4.0 3.2 69 FeO(OH) 94.976.8 0.0 14.6 1.5 70 Grade F-100 89.8 74.5 0.0 0.0 38.3 71 Grade F-186.8 73.8 0.0 0.1 2.5 72 Davicat ZL WR Grace synthetic 85.3 58.8 0.0 0.46.4 5151 zeolite 73 CO/Al2O3 8% Co on Al2O3 95.2 58.2 0.0 5.4 1.5 74Grade F-4 86.8 57.0 0.0 0.0 20.8 75 CoS/MoS 96.2 55.8 0.0 5.8 0.0 76Ru/TiO2 5% Ru on TiO2 79.7 52.2 0.0 5.2 13.2 77 WO3/ZrO2 99.7 44.5 0.00.4 0.4 78 Co/Al2O3 88.1 44.2 0.0 5.6 5.9 79 CBV 720 ZeolystInternational 94.3 44.0 0.0 0.2 3.8 zeolite 80 Pd/Al2O3 0.5% Pd on Al2O389.9 36.2 0.0 7.0 6.6 81 Pd/C 0.5% Pd on 89.9 35.5 0.0 0.0 1.5 carbon(Degussa) 82 Rh/C 5% Rh on carbon 68.1 35.3 0.0 0.0 1.1 powder(Johnson-Matthey) 83 Rh/Al2O3 0.5% Rh on Al2O3 95.6 33.1 0.0 2.5 1.2 84Rh/Al2O3 97.4 28.5 0.0 3.3 0.4 85 6757-49-1 83.7 28.1 0.0 5.2 2.1 86ALZ5C-4D 95.7 28.0 0.0 0.1 13.3 87 Nb2O5/Al2O3 98.6 26.5 0.0 4.0 62.4 88Ru/C 0.7% Ru on carbon 94.1 26.1 0.0 0.0 3.7 89 Ni/Re/ZrO2 4.9% Ni/0.7%88.7 25.9 0.0 0.3 7.6 Re on ZrO2 90 P25 98.5 25.6 0.0 4.2 0.6 91Ag2O/CuO 91.1 21.7 0.0 0.4 15.6 92 G-89 Cu Cr/Mn 90.0 21.6 0.0 0.3 1.193 Cr-0211T Cr/ZrO2 on alumina 94.8 18.4 0.0 2.2 0.0 94 Ni/Re/TiO2 4.9%Ni/1% 93.7 16.0 0.0 0.6 6.7 Re on rutile TiO2 95 Rh/Al2O3 1% Rh on Al2O394.8 14.1 0.0 0.6 8.4 96 Pd/C 1.5% Pd on 90.2 14.0 0.0 0.0 1.6 carbon(G277) 97 MELCAT 94.5 13.7 0.0 4.9 4.5 880/01 98 MoO3/ZrO2 98.6 10.5 0.06.7 0.9 99 G-22/2 47% CuO/34% Cr2O3/ 97.4 10.2 0.0 0.2 1.4 6% BaO onSiO2 100 Rh/Al2O3 98.8 6.5 0.0 0.8 2.4 101 Cr-0211T 99.1 6.4 0.0 1.7 0.6102 Rh/C 5% Rh on carbon 80.3 5.2 0.0 0.0 1.6 powder (Engelhard) 103ZrO2/SO4 94.7 5.2 0.0 3.9 0.9 104 ZrO2/WO3 99.5 2.8 0.0 2.6 1.0 105T-869 Si/Al 99.4 1.8 0.0 1.1 0.6 106 Zr-0404 99.4 1.3 0.0 1.4 0.3 107Shot Coke 97.8 1.2 0.0 0.0 0.4 * Composition details are not availablefor some commercially-obtained catalysts.

Effect of Support Material on Palmitic Acid Decarboxylation: Foursupport materials (carbon, ZrO₂, Al₂O₃, and TiO₂) were evaluated fortheir effect on palmitic acid decarboxylation. The results are shown inTable 2 and FIG. 2. Complete conversion of palmitic acid was obtainedwith various catalysts on carbon, ZrO₂, Al₂O₃, and TiO₂ supports.

TABLE 2 Mass Pentadecane Ketone Others Catalyst Composition DetailsRecovery Conversion Yield Yield Yield 1 Pt/Ge/C 5% Pt/Ge on carbonpowder 61.0 100.0 107.5 0.0 3.4 2 Pt/C 48.9 83.2 33.4 0.0 9.4 3 Pt/Sn/C1.5% Pt/0.15% Sn on 57.7 85.7 31.1 0.3 6.9 carbon powder 4 Pt/C 5% Pt onNorit ROX 46.3 100.0 16.3 0.0 3.1 5 Pt/Ru/C 1.5% Pt/0.15% Ru on 83.858.6 15.8 0.2 10.6 carbon powder 6 Pt(S)/C 3% Pt (sulphited) on 76.526.8 1.1 0.0 8.4 carbon powder 7 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO290.0 88.8 54.4 0.9 27.9 8 WO3/Pt/ZrO2 12% W03/0.7% Pt on ZrO2 64.6 97.235.1 0.2 17.6 9 Pt/ZrO2 0.7% Pt on ZrO2 93.5 30.6 16.9 0.2 7.1 10Pt/ZrO2 0.7% Pt on ZrO2 92.8 29.7 15.5 0.4 11.5 11 Pt/ZrO2 0.7% Pt onZrO2 92.5 29.4 16.3 0.4 7.5 12 Pt/ZrO2 0.7% Pt on ZrO2 93.3 28.4 12.01.1 12.8 13 MoO3/Pt/ZrO2 7.8% MoO3/0.7% Pt on ZrO2 88.7 57.8 34.6 0.510.6 14 MoO3/Pt/ZrO2 7.8% MoO3/0.7% Pt on ZrO2 92.4 42.0 21.7 1.6 4.3 15WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 70.7 99.6 42.1 0.2 10.8 16WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 82.0 93.0 37.8 0.5 11.4 17 Pt/ZrO20.7% Pt on ZrO2 81.8 36.4 0.0 0.3 7.9 18 WO3/Pt/ZrO2 12% WO3/0.7% Pt onZrO2 64.0 100.0 27.8 0.0 8.4 19 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 78.4100.0 41.7 0.0 13.5 20 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 70.6 92.625.1 0.0 8.9 21 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 82.6 82.5 32.6 0.013.0 by MVD 22 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 75.3 100.0 56.0 0.228.8 23 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 81.8 98.4 44.7 0.3 31.7 24WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 78.6 100.0 43.0 25 WO3/Pt/ZrO2 12%WO3/0.7% Pt on ZrO2 78.0 68.3 37.5 0.2 21.7 26 WO3/Pt/ZrO2 12% WO3/0.7%Pt on ZrO2 65.6 100.0 32.8 0.0 10.8 27 WO3/Pt/ZrO2 12% WO3/0.7% Pt onZrO2 62.5 100.0 20.4 28 Pt/Al2O3 2% Pt on Al2O3 80.4 70.2 29.5 3.7 7.829 Pt/Al2O3 5% Pt on Al2O3 90.6 93.8 63.1 0.4 4.3 30 Pt/Al2O3 3% Pt onAl2O3 81.9 72.4 2.3 4.4 5.0 31 Pt/Al2O3 3% Pt on Al2O3 83.0 82.6 0.3 2.22.7 32 Pt/Al2O3 2% Pt on Al2O3 56.9 86.3 10.6 1.8 4.3 33 Pt/TiO2 5% Pton TiO2 78.9 99.5 82.7 0.0 16.3 34 Pt/TiO2 0.7% Pt on TiO2 (900 C.calcine) 93.1 13.7 0.0 0.0 0.2 35 Pt/TiO2 0.7% Pt on TiO2 (450 C.calcine) 72.1 68.1 0.0 7.7 8.0 36 Pt/TiO2 0.7% Pt on TiO2 (uncalcined)79.8 72.5 15.0 0.0 13.5 37 Pt/ZrO2 5% Pt on ZrO2 93.4 59.8 51.8 0.3 0.5

Effect of Pt and WO₃ Concentrations on Palmitic Acid Decarboxylation: AWO₃/Pt/ZrO₂ catalyst formulation was selected for further development.The effects of percent Pt and WO₃ were evaluated to determine suitablecombinations with a desirable balance between palmitic acid conversionand pentadecane yield and metal loading. Catalysts ranging from 6-30 wt% WO₃ and 0.1-1.5 wt % Pt, relative to total catalyst mass were preparedand evaluated. Unexpectedly superior results were obtained withcatalysts of low metal loading, having 6-12 wt % WO₃ and 0.4-0.7 wt %Pt. Lower metal loading reduces the value/cost of the catalyst,especially important for expensive metals such as Pt. The results areshown in Table 3 and FIGS. 3 and 4. In FIG. 3, the amount of conversionreached a plateau around 0.7 wt % Pt, where the addition of moreplatinum did not improve the amount of conversion of the feedstock. Asimilar plateau can be seen in FIG. 4; starting at 12% WO₃. The additionof more tungsten oxide did not improve the amount of conversion. Inaddition a significantly higher yield of pentadecane was not noted whenthe amounts of either metal were increased beyond 12% WO₃ and/or 0.7%Pt.

Due to the screening nature of the tests and use of high throughputtechnology, mass recovery data provides an indication of the potentialintegrity of the sample during testing. Data scatter is attributable torunning several different batch tests. Variances in mass balance producemore scatter. A low mass recovery is indicative of an individual vialleak, and data may not be of equal quality to data with high massrecovery since the more volatile components would be more prone tovaporization and leaking from the individual vial.

TABLE 3 Mass Pentadecane Others Catalyst Pt % WO3% Recovery ConversionYield Yield 1.5% Pt/30% WO3 1.5 30 89.3% 100.0% 64.7% 11.6% 1% Pt/30%WO3 1 30 76.5% 100.0% 46.7% 8.7% 1.5% Pt/12% WO3 1.5 12 74.1% 100.0%43.6% 11.5% 1.5% Pt/20% WO3 1.5 20 73.6% 100.0% 41.2% 9.7% 1% Pt/20% WO31 20 71.4% 100.0% 37.4% 10.0% 0.7% Pt/20% WO3 0.7 20 41.1% 100.0% 0.0%0.8% 0.6% Pt/20% WO3 0.6 20 46.9% 99.3% 1.4% 1.6% 0.7% Pt/12% WO3 0.7 1265.0% 95.2% 20.2% 8.1% 0.7% Pt/17% WO3 0.7 17 65.2% 93.7% 16.6% 7.2%0.7% Pt/12% WO3 0.7 12 80.4% 91.7% 32.2% 13.1% 0.7% Pt/20% WO3 0.7 2091.4% 88.5% 49.3% 14.9% 0.5% Pt/15% WO3 0.5 15 67.4% 86.1% 12.3% 6.7%0.4% Pt/12% WO3 0.4 12 57.8% 85.8% 1.4% 3.0% 0.6% Pt/12% WO3 0.6 1280.9% 84.8% 28.5% 10.7% 1.5% Pt/6% WO3 1.5 6 92.0% 81.2% 55.2% 10.9%0.4% Pt/15% WO3 0.4 15 60.8% 80.9% 1.4% 3.6% 0.6% Pt/17% WO3 0.6 1792.1% 80.8% 42.6% 12.0% 0.5% Pt/12% WO3 0.5 12 92.3% 78.4% 39.9% 13.9%0.4% Pt/30% WO3 0.4 30 84.5% 77.3% 26.0% 10.0% 0.4% Pt/12% WO3 0.4 1292.4% 76.2% 33.0% 14.4% 0.4% Pt/15% WO3 0.4 15 73.9% 74.7% 9.1% 8.0%0.5% Pt/20% WO3 0.5 20 93.0% 73.2% 40.7% 12.3% 0.4% Pt/17% WO3 0.4 1764.7% 73.0% 2.1% 4.1% 1% Pt/6% WO3 1 6 93.0% 70.2% 37.0% 9.6% 0.5%Pt/17% WO3 0.5 17 93.1% 64.0% 30.1% 10.4% 0.4% Pt/20% WO3 0.4 20 93.8%63.1% 34.9% 11.5% 0.4% Pt/20% WO3 0.4 20 93.9% 63.0% 31.4% 11.5% 0.7%Pt/6% WO3 0.7 6 89.5% 60.8% 23.7% 8.8% 0.4% Pt/6% WO3 0.4 6 94.9% 51.3%20.0% 9.6% 0.1% Pt/30% WO3 0.1 30 86.0% 32.6% 0.0% 3.3% 0.1% Pt/12% WO30.1 12 92.9% 31.0% 0.0% 5.3% 0.1% Pt/20% WO3 0.1 20 97.0% 27.5% 1.0%7.5% 0.4% Pt 0.4 0 97.5% 25.3% 8.1% 6.4% 0.1% Pt/6% WO3 0.1 6 98.5%16.4% 0.0% 4.7% 0.7% Pt/12% WO3 0.7 12 98.8% 10.6% 0.0% 1.8%  30% WO3 030 99.3% −1.6% 0.0% 1.6%

Effect of ZrO₂ Support on Palmitic Acid Decarboxylation: Seven ZrO₂supports were tested and compared to the support used for the initialcatalyst preparation, 12% WO₃/0.7% Pt on Engelhard ZrO₂ support lot 0403(BASF Corporation, Florham Park, N.J.). Each catalyst was prepared bythe same robotic system at equivalent metal loading relative to thetotal mass of the catalyst. The results are shown in Table 4 and FIGS. 5and 6. FIG. 5 includes the data for each individual trial, and FIG. 6provides an average for all samples of a particular catalyst. Ingeneral, palmitic acid conversion and product yields were quiteconsistent. In each case, the major product was C15.

TABLE 4 Mass Catalyst Recovery Conversion C15 Yield Others Yield Zr0403_36¹ 74.8 98.3 26.0 15.0 Zr 0403_43-54¹ 77.3 83.8 33.4 13.9 Zr0404A¹ 74.9 96.9 28.5 16.6 Zr 0404B¹ 78.1 88.5 25.6 13.1 Zr 0404C¹ 78.283.9 30.9 14.7 Zr 0404D¹ 75.6 94.2 32.1 14.6 NorPro² 78.4 83.0 30.3 15.3Baseline 77.3 86.7 34.3 20.6 ¹BASF Corporation Florham Park, NJ²Saint-Gobain NorPro, Canton, OH

Effect of Carbon Support on Palmitic Acid Decarboxylation: Screeningexperiments were conducted with various catalysts with carbon supportsto evaluate their ability to decarboxylate palmitic acid. The catalystsalso were compared to catalysts having inorganic supports such as ZrO₂and TiO₂. As shown in FIG. 7, the primary product was pentadecane inmost instances. Surprisingly superior results were obtained with the 5%Pt/Ge/C with more than 95% of the product being pentadecane within theexperimental error of the screening tests. In contrast, two differentPt/C catalysts resulted in products including less than 40% pentadecaneor less than 20% pentadecane.

Catalyst Screening for Oleic Acid Decarboxylation: Catalysts werescreened for their ability to deoxygenate oleic acid. Due to its doublebond, oleic acid is capable of undergoing several reactions when exposedto the disclosed catalysts. These reactions includedeoxygenation/decarboxylation/decarbonylation/dehydration, hydrogenation(saturation), cracking, dehydrogenation/aromatization,alkylation/cyclization/dimerization/oligomerization, and isomerization.The results are shown in FIGS. 8 and 9 and Table 5. FIG. 8 shows theeffects of various catalyst compositions on oleic acid. The most commonproducts included C17, stearic acid, and unsaturated C18 isomers ofoleic acid. C17 refers to compounds having 17 carbon atoms. The majorC17 product was heptadecane; other products included alkyl-branchedaromatics. The C17 and stearic acid yields produced by several of thecatalysts are shown in FIG. 9. Pt/Ge and Pt/Sn on carbon providedsuperior results for decarboxylating oleic acid with no dimerization oroligomerization. When Pt/Ge/C was the catalyst, more than 95% of theproduct was heptadecane, with the remaining products includingpentadecane and alkyl-branched aromatics. When Pt/Sn/C was the catalyst,more than 85% of the product was heptadecane. In contrast, when using aPt/C catalyst, less than 60% of the product was heptadecane.

TABLE 5 Catalyst Mass Stearic Acid C17 Composition Composition DetailsRecovery Conversion Yield Yield 1 Pt/Ge/C 5% Pt/Ge on carbon 88.5 100.00.6 112.2 2 Pt/Sn/C 1.5% Pt/0.15% Sn on carbon 85.5 99.6 5.9 86.7 3Pt/Hyp 5% Pt on Hyperion carbon 88.7 99.4 19.4 59.6 4 Pt/Al2O3 5% Pt onAl2O3 93.1 98.8 21.6 47.8 5 WO3/Pt/ZrO2 12% WO3/0.7% Pt on ZrO2 97.399.6 16.3 18.9 6 Re/Pt/Norit 5% Re/2% Pt on Norit carbon 95.1 92.1 51.817.4 7 Pt/TiO2 5% Pt on TiO2 94.9 83.3 28.7 17.3 8 Re/Ir/Norit 5% Re/5%Ir on Norit 91.2 70.3 32.6 8.6 9 Re/Ru/Norit 5% Re/3% Ru on Norit 91.960.0 18.3 4.0 10 Ni/Re/Pt/Hyp 5% Ni/1% Re/0.02% Pt on 93.4 76.3 24.9 2.4Hyperion 11 Ir/Ni/Hyp 7% Ir/3% Ni on Hyperion 88.4 86.2 25.6 2.4 12Ru/Au/Norit 4.8% Ru/1% Au on Norit 96.6 40.5 18.8 2.0 13 Re/Ru/Hyp 5%Re/3% Ru on Hyperion 95.1 49.3 10.7 1.9 14 Pt/ZrO2 5% Pt on ZrO2 98.755.8 27.0 1.4 15 Ru/Hyp 5% Ru on Hyperion 97.5 63.7 13.5 1.4 16 Ru/GrafC7% Ru on 1.8-mm graphitic 98.4 34.3 11.3 1.0 carbon (Engelhard No. PM0400007, BASF) 17 Ru/Cd/Pt/Hyp 5% Ru/0.5% Cd/ 94.3 43.6 12.8 0.9 0.02%Pt on Hyperion 18 MoO3/Pt/ZrO2 7.8% MoO3/0.7% Pt on ZrO2 102.2 32.7 20.60.7 19 Ir/In/Hyp 7% Ir/3% In on Hyperion 97.2 46.4 11.4 0.3 20 Re/Norit5% Re on Norit 99.2 29.2 10.8 0.2 Note: GrafC (graphitic carbon, BASFCorporation, Florham Park, NJ), Hyp (multi-walled carbon nanotubes,Hyperion Catalysis International, Cambridge, MA) and Norit (Norit ROX,acid-washed, extruded activated carbon, Norit Americas, Inc., Marshall,TX) are all forms of carbon.

The compounds produced by exposing oleic acid to a catalyst having 1.5wt % Pt and 0.15 wt % Sn on carbon powder were evaluated by gaschromatography/mass spectroscopy (GC/MS). FIG. 10 is a GC trace of theproducts. The MS fragmentation patterns corresponding to the aromaticcompound with a mass of 232 amu were identified as the chromatographicpeaks obtained at 4.911 minutes, 5.002 minutes, 5.125 minutes, and 5.262minutes, and are shown in FIGS. 11-14, respectively. Although no matcheswere found in MS libraries, the closest C17 aromatic compounds appearedto be 2-methyl-2-phenyl decane (molecular weight fragments of 119, 91,120, and 105) and 2-phenyl undecane (molecular fragments of 105, 106,91, and 232). Other close MS fragmentation matches included methylisobutyl benzene and 1,3-dimethylbutyl benzene but these compounds areof different mass.

Comparison of Products Produced from Palmitic Acid and Oleic Acid Usinga 5% Pt/Ge/C Catalyst: Palmitic acid and oleic acid were individuallyexposed to a 5% Pt/Ge/C catalyst in screening tests, and the productswere analyzed by gas chromatography with a flame ionization detector(GC-FID). FIG. 15 is an overlay of the GC-FID traces of the productsformed from catalysis of palmitic acid and oleic acid. The palmitic acidproducts are shown as a solid line, and the oleic acid products areshown as a dashed line. In each case, methyl-branched hydrocarbonsexited the column first, followed by straight-chain hydrocarbons andthen aromatic compounds. The tall, overlapping peaks at about 2.5minutes are pentadecane. The tall peak at about 3.35 minutes isheptadecane. The shoulder peak just in front of heptadecane is anaromatic compound, as are the peaks following it. The peaks from about3.4 to about 3.7 minutes are thought to be alkyl-substituted aromaticcompounds. The small peaks seen from about 1-3 minutes are thought to bemono-methyl branched hydrocarbons. Thus, the major product of palmiticacid decarboxylation was pentadecane with a small amount of hexadecaneand about 3% of other products. Oleic acid decarboxylation producedprimarily heptadecane with a small amount of pentadecane and minoramounts of other products. It can be seen that the oleic acid productsincluded a much higher ratio of aromatic compounds to methyl-branchedhydrocarbons as compared to the palmitic acid products.

Example 2 Platinum on Metal Oxide Catalysts Catalyst Synthesis:

Catalyst 1 (WO₃/ParO₂): BASF Zr-0403 (BASF Corporation, Florham Park,N.J.), an engineered (tableted) zirconia support with a cornstarchbinder, was used as the catalyst support. The support was calcined at450° C. for 6 hr in air. A 5° C./min ramp from room temperature to 450°C. and 10° C./min ramp back to room temperature were employed. Identicaltemperature ramps were subsequently used in all calcination steps inthis catalyst preparation. Next, an ammonium metatungstate hydratesolution was added drop-wise to the support to the point of incipientwetness. The amount of ammonium metatungstate hydrate was added so thatthe amount of tungstate present on the catalyst would be 12 wt % WO₃.The support was first dried in flowing warm air from a heat gun for 30min and subsequently dried at 120° C. for 2.0 hr. Following drying, thecatalyst was calcined at 850° C. for 2.0 hr. After calcination, anaqueous platinum ethanolamine (Pt-A) solution was added drop-wise to thecatalyst support such that the support again reached incipient wetness.Pt-A solution was added so that the final catalyst would be 0.7 wt % Pt.The pellets were dried under flowing heated air produced from a heat gunwhile tumbling for 30 min and further dried in air at 120° C. for 2.5hr. The catalyst was calcined at 450° C. for 2 hr. After calcination,Catalyst 1 was ground with an alumina mortar and pestle and the −30/+80mesh fraction was collected via sieving and used in Runs 1-5.

Catalyst 2 (WO₃/Pt/ZrO₂): NorPro® SZ31164 engineered (tableted) zirconiasupport was initially ground with an alumina mortar and pestle. The−30/+80 mesh fraction was then collected via sieving. The zirconiasupport was calcined at 450° C. for 6 hr, with 5° C./min and 10° C./minramps from calcination temperature and back to room temperature,respectively. Identical temperature ramps were subsequently used in allcalcination steps in this catalyst preparation. Following calcination,an aqueous solution of ammonium metatungstate hydrate was added to thezirconia such that the incipient wetness point was reached. The amountof ammonium metatungstate hydrate was added so that 12 wt % WO₃ would bepresent on the catalyst following calcination. After the addition of theammonium metatungstate hydrate, the support was dried in flowing heatedair from a heat gun while tumbling for 45 min, followed by drying at120° C. for 1.0 hr in air. The support was then calcined at 850° C. for2.0 hr. After calcination, aqueous platinum ethanolamine (Pt-A) solutionwas added drop-wise to the support such that incipient wetness point ofthe support was again reached. Pt-A solution was added so that the finalcatalyst would be 0.7 wt % Pt. After addition of the Pt-A solution, thecatalyst was dried for 45 min while tumbling in air at room temperaturefollowed by drying at 120° C. for 1.0 hr. The support was subjected to afinal calcination at 450° C. for 2.0 hr. Catalyst 2 was used in Run 6without further modification.

Catalyst 3 (WO₃/Pt/ZrO₂): BASF Zr-0403, an engineered ZrO₂ support, wasused in this preparation. The support contained a graphite binder. Thesupport was calcined at 450° C. for 6 hr using a 10° C./min ramp andtaken out of the oven at the end of the 6 hr soak and placed in adesiccator. Upon cooling, this support was subjected to tungstateaddition using an aqueous ammonium metatungstate hydrate solution viathe incipient wetness technique. The amount of ammonium metatungstatehydrate was added so that 12 wt % WO₃ would be present on the catalystfollowing calcination. After drying, the sample was calcined at 850° C.for 2 hr using 5° C./min and 10° C./min ramps from calcinationtemperature and back to room temperature, respectively. Identicaltemperature ramps were subsequently used in all calcination steps inthis catalyst preparation. Pt was then added to the tungstated supportvia the incipient wetness technique such that 0.7 wt % Pt was present.The support was dried in flowing heated air from a heat gun for 1.5 hrand further dried for 2 hr at 120° C. After calcination at 450° C. for 2hr, this catalyst was designated Catalyst 3.

Catalysts 4 and 5 (Pt/ZrO₂): Two lots of BASF Zr-0403 were calcined at850° C. for 2 hr using 5° C./min and 10° C./min ramps from calcinationtemperature and back to room temperature, respectively. The supportswere designated G and C for the graphite and cornstarch binder supports,respectively.

A portion of supports G and C were separately treated with aqueous Pt-Asolution to produce a Pt/ZrO₂ catalyst with 0.7 wt % Pt. The solutionwas added via the incipient wetness technique. After application of theaqueous Pt-A solution, the supports were dried in heated flowing airfrom a heat gun for 15-20 min. The catalysts were then dried for 6-7 hrsat 120° C. and subsequently calcined at 450° C. for 2 hr. The Pt/ZrO₂catalyst prepared from graphite bound support was designated Catalyst 4while the catalyst prepared from cornstarch bound support was designatedCatalyst 5.

Catalyst 6 (MoO₃/Pt/ZrO₂): BASF Zr-0403 with a graphite binder wasprepared with MoO₃ instead of WO₃. The Zr-0403 was calcined at 450° C.for 6 hr using a with 5° C./min and 10° C./min ramps from calcinationtemperature and back to room temperature, respectively. Identicaltemperature ramps were subsequently used in all calcination steps inthis catalyst preparation. Next, an aqueous solution of ammoniumheptamolybdate hydrate was added to the catalyst via the incipientwetness technique. The amount of molybdate was added such that theconcentration would be 7.8 wt % MoO₃, which is equivalent on a molarbasis to 12 wt % WO₃. The support was then dried with flowing heat froma heat gun for 30 min, flowing by heating in air 120° C. for 2 hr andsubsequently calcined at 850° C. for 2 hr. The MoO₃/ZrO₂ support wasthen divided and one portion was modified with 0.7 wt % Pt via anaqueous Pt-A solution using the incipient wetness technique. Heat wasapplied from a heat gun while tumbling for 0.5 hr followed by drying at120° C. for 2.25 hr. The catalyst was then calcined at 450° C. for 2 hrand designated Catalyst 6.

Catalyst 7 (WO₃/Pt/ZrO₂, prepared with platinum acetylacetonate): AnEngelhard-0403 engineered (tableted) zirconia support (BASF Corporation)was initially calcined at 450° C. for 4.5 hr, with 5° C./min and 10°C./min ramps from calcination temperature and back to room temperature.The support was then ground with an alumina mortar and pestle. The−30/+80 mesh fraction was then collected via sieving. Next, an aqueoussolution of ammonium metatungstate hydrate was added to the zirconiasuch that the incipient wetness point was reached. The amount ofammonium metatungstate hydrate was added so that 12 wt % WO₃ would bepresent on the catalyst following calcination. After the addition of theammonium metatungstate hydrate, the support was dried at roomtemperature while tumbling for 15 min, followed by drying at 120° C. for2.0 hr in air. The support was then calcined at 850° C. for 2.0 hr withramps identical to the first calcination step.

The catalyst support and platinum acetylacetonate (Pt-acac) were chargedto a 50 mL round bottom flask. The amount of Pt-acac added was such thatthe final Pt loading of the catalyst would be 0.7 wt %. The round bottomflask was placed on a rotary evaporator and vacuum was applied to theflask; the pressure was set to 10 torr. The flask was set to rotate at120 rpm. The rotating flask was then lowered so that it was rotating incontact with a heating mantle. The heating mantle was controlled with aVariac®. A thermocouple was placed between the heating mantle androtating round bottom flask. Additionally, a heat gun was positionedapproximately 4 inches above the rotating flask so that the heat gun wasaimed at the top of the round bottom flask.

Initially, the flask was set to rotating for 10 min with no heat appliedin order to induce mixing of the catalyst support and Pt-acac. Next,heat was applied with the heating mantle and heat gun such that thethermocouple between the round bottom flask and heating mantle read 180°C. The ramp from room temperature to 180° C. took 5-10 min. After 10 minat 180° C., the temperature was increased to 220° C. and held for 30min. The ramp from 180° C. to 220° C. took 3-5 min. After treatment at220° C., the temperature was increased a final time to 240° C. and heldfor 30 min. The ramp from 220° C. to 240° C. took 3-5 min. Aftertreatment at 240° C., the samples were cooled and subsequently calcinedat 350° C. for 3 hr in air with a 5° C./min ramp from room temperatureand a 10° C./min ramp back to room temperature. The WO₃/Pt/ZrO₂ catalystprepared in this manner was designated Catalyst 7.

Catalysts 8-10 (Pt/TiO₂): Three titania supports were prepared fromDegussa TiO₂ Lot DFH-14-231E. One titania support was uncalcined, asecond was calcined at 450° C. for 2 hr and a third was calcined at 900°C. for 2 hr. Ramps of 5° C./min and 10° C./min to and from calcinationtemperature were used in all heat treatments. After calcination, eachsupport was ground with an alumina mortar and pestle and the −30/+80mesh fraction was collected via sieving.

Separately, each catalyst support was charged to a 50 mL round bottomflask with Pt-acac. The amount of Pt-acac added was such that the finalPt loading of the catalyst would be 0.7 wt %. The round bottom flask wasplaced on a Rotovap and vacuum was applied to flask; the pressure wasset to 10 torr. The flask was set to rotate at 120 rpm. The rotatingflask was then lowered so that it was rotating in contact with a heatingmantle. The heating mantle was controlled with a Variac®. A thermocouplewas placed between the heating mantle and rotating round bottom flask.Additionally, a heat gun was positioned approximately 4 inches above therotating flask so that the heat gun was aimed at the top of the roundbottom flask.

Initially, the flask was set to rotating for 10 min with no heat appliedin order to induce mixing of the catalyst support and Pt-acac. Next,heat was applied with the heating mantle and heat gun such that thethermocouple between the round bottom flask and heating mantle read 180°C. The ramp from room temperature to 180° C. took 5-10 min. After 10 minat 180° C., the temperature was increased to 220° C. and held for 30min. The ramp from 180° C. to 220° C. took 3-5 min. After treatment at220° C., the temperature was increased a final time to 240° C. and heldfor 30 min. The ramp from 220° C. to 240° C. took 3-5 min. Aftertreatment at 240° C., the samples were cooled and subsequently calcinedat 350° C. for 3 hr in air with a 5° C./min ramp from room temperatureand a 10° C./min ramp back to room temperature. The Pt/TiO₂ catalystsprepared above were designated Catalysts 8, 9, and 10 for the supportscalcined at 900° C., 450° C. and uncalcined, respectively.

Catalyst 11 (Pt/ZrO₂): BASF Zr-0404 ZrO₂ support was ground and sievedto −30/+80 mesh. Pt was then applied via a Pt-acac precursor in asimilar manner to the above catalyst preps. The amount of Pt added wassuch that the catalyst would contain 0.7 wt % Pt. A key difference fromthe previously described Pt-acac catalyst preparation method was thetemperature was ramped directly from room temperature to 240 and heldfor 20 min as opposed to intermediate soaks at 180° C. and 220° C.Additionally, the round bottom flask was rotated at 85 RPM as opposed to120 RPM. After calcination at 350° C. for 3 hr, this catalyst wasdesignated Catalyst 11. The catalyst was reduced at 350° C. in H₂flowing at 200 SCCM for 4 hr prior to Combi testing.

Catalyst 12 (WO₃/Pt/ZrO₂): A support was prepared from BASF Zr-0403 witha graphite binder present. The support was calcined at 450° C. for 6 hrwith a 10° C./min ramp to calcination temperature. The support was thenremoved from the oven while still hot at the end of the 6 hr soak at450° C. An aqueous solution of ammonium metatungstate hydrate wasapplied to the support via the incipient wetness technique such that thenominal concentration of WO₃ would be 12 wt %. The support was thencalcined at 850° C. for 2 hr using a 5° C./min ramp to calcinationtemperature and a 10° C./min ramp back to room temperature. The supportwas then ground and the −30/+80 mesh fraction was collected via sieving.Pt-acac was then applied in an identical manner as used during thepreparation of Catalyst 11. After calcination at 350° C. for 3 hr, thiscatalyst was designated Catalyst 12. The catalyst was reduced 350° C. inH₂ flowing at 200 SCCM for 4 hr prior to Combi testing.

Catalyst 13 (WO₃/Pt/ZrO₂): BASF Zr-0403 (BASF Corporation, Florham Park,N.J.), an engineered (tableted) zirconia support with a cornstarchbinder, was used as the catalyst support. The support was ground with amortar and pestle and the −30/+80 mesh fraction was collected viasieving. The support was calcined at 450° C. for 6 hr in air. A 10°C./min ramp from room temperature to 450° C. and 20° C./min ramp back toroom temperature were employed. After calcination, an ammoniummetatungstate hydrate solution was added drop-wise to the support to thepoint of incipient wetness. The amount of ammonium metatungstate hydratewas added so that the amount of tungstate present on the catalyst wouldnominally be 12 wt % WO₃. The support was first dried in flowing warmair from a heat gun for 35 min and subsequently dried at 120° C.Following drying, the catalyst was calcined at 850° C. for 2.0 hr with aramp of 5° C. from room temperature to 850° C. and a 10° C./min rampback to room temperature. After calcination, an aqueous platinumethanolamine (Pt-A) solution was added drop-wise to the catalyst supportsuch that the support again reached incipient wetness. Pt-A solution wasadded so that the final catalyst would be 0.7 wt % Pt. The catalyst wasdried under flowing room temperature air while tumbling for 1.0 hr.Heated air was then applied to the catalyst while tumbling for 45 min.Finally, the catalyst was dried in air at 120° C. for 4 hr. Afterdrying, the catalyst was calcined at 450° C. for 2 hr with a temperatureramp of 5° C./min to 450° C. and a 10° C./min ramp back to roomtemperature.

Catalyst 1 Analysis:

Run 1: Catalyst 1 was evaluated for its ability to decarboxylatepalmitic acid in Run 1. An up-flow, 6 cm³ column was packed with 13.68 gof Catalyst 1, which had been ground and sieved to −30/+80 mesh. Thecolumn was brought to an initial temperature of 250° C. and purged with2.5 mL/min N₂ before beginning a feed of palmitic acid. The N₂ remainedon at 2.5 mL/min for the duration of the experiment. Nine samples weretaken, with sample acquisition times of 20-50 min. In other words, eachsample was collected over a 20-50 minute period of time. The temperaturewas increased to 275° C. at the beginning of sample 4 acquisition andmaintained at 275° C. for samples 4-9. The column was operated at aweight hourly space velocity (WHSV) of 0.37 hr⁻¹ for samples 1-6, and0.74 hr⁻¹ for samples 7-9. Samples 1-9 were analyzed via GC-FID asdescribed in Example 1 to determine the percentage of deoxygenatedproducts, the amount of palmitic acid remaining, and the total massbalance recovered. The amount of CO₂ released was determined using theoff-gas flow rate and gas composition data obtained by GC. CO₂measurement was not performed on samples 2, 5, and 8.

The results of Run 1 are shown in FIGS. 16 and 17. As shown in FIG. 16,samples 1-6 contained no residual palmitic acid after exposure to thecatalyst, and were completely converted to deoxygenated products (e.g.,pentadecane) and CO₂. FIG. 17 provides a comparison of percentdecarboxylation and percent palmitic acid conversion over about 450minutes time-on-stream (TOS). Palmitic acid conversion was at or near100% through 400 minutes, with a slight decrease after 400 minutes.Notably, percent decarboxylation is closely correlated to percentpalmitic acid conversion, indicating that the primary product wasdecarboxylated palmitic acid, primarily pentadecane.

Run 2: Catalyst 1 was used for Run 2. Conditions were similar to Run 1,but the temperature was initially 280° C. and was increased to 290° C.after sample 2. In Run 2, the column was operated at WHSV=0.37 hr⁻¹,with 40-90 minute sample acquisition times. Ten samples were collectedand analyzed.

The results of Run 2 are shown in FIGS. 18 and 19. As illustrated inFIG. 18, as the temperature increased to 290° C., the percent residualpalmitic acid dropped to near zero. FIG. 19 demonstrates that percentdecarboxylation is closely correlated to percent palmitic acidconversion. Palmitic acid conversion was 90-100% at a temperature of290° C. over a time period of 200-800 minutes TOS.

Run 3: Catalyst 1 was used for Run 3, with an oleic acid feed for thefirst 8 samples, and a palmitic acid feed for the last two samples. Thecolumn was purged with 2.5 mL/min N₂ before beginning the oleic acidfeed. Because Run 3 was performed after Runs 1-2, some residual palmiticacid remained in the column and is seen in Sample 1. The column wasoperated at 295° C. with WHSV=0.36 hr⁻¹. Sample acquisition times were45-100 minutes. At the beginning of Sample 9 acquisition, the feed wasswitched to palmitic acid, and WHSV=0.37 hr⁻¹. Ten samples werecollected and analyzed.

The results of Run 3 are shown in FIGS. 20 and 21. With respect to FIG.20, exposure of unsaturated oleic acid (18:1) to Catalyst 1 produced amixture of products, including deoxygenated products (e.g., C17) andsaturated stearic acid (18:0). The majority of the products weredeoxygenated as expected. However, in addition to decarboxylation,Catalyst 1 has some dehydrogenation ability. Because oleic acid ishydrogen-deficient, any dehydrogenation of oleic acid moleculesresulting from exposure to Catalyst 1 can result in hydrogenation ofother oleic acid molecules, producing some stearic acid. Some residualpalmitic acid also was seen in Samples 1-6.

It was observed that the products for Samples 1-8, including CO₂,totaled only 30-50% of the mass balance. Catalyst 1 is a somewhat acidiccatalyst and can cause alkylation reactions as well as decarboxylationwhen unsaturated fatty acids are used. Thus, the catalyst alkylates asignificant portion of the oleic acid molecules, forming heavierproducts, e.g., C36, C54, etc., which are too heavy for GC-FID analysis.

FIG. 21 shows that substantially 100% of the oleic acid was convertedover a time period of 600 minutes TOS. However, decarboxylation was20-40%, providing further indication that a significant percentage ofthe unsaturated oleic acid was alkylated by the catalyst instead,thereby undergoing dimerization or oligomerization. When the feed wasswitched to saturated palmitic acid, decarboxylation and percentconversion were again closely correlated.

Run 4: Catalyst 1 was used for Run 4, with a palmitic acid feed. Thecolumn was operated at 295° C. with WHSV=0.37 hr⁻¹. The column wasinitially purged with 2.5 mL/min N₂, but the purge gas was switched to3.5 mL/min 92% Ar/8% H₂ mix at the beginning of Sample 7 acquisition.Ten samples were collected with sample acquisition times of 50-85minutes.

The results of Run 4 are shown in FIGS. 22 and 23. FIG. 22 shows thatpalmitic acid conversion remained fairly steady at near 80% over thetime period of 800 minutes TOS. FIG. 23 shows that conversion ofpalmitic acid remained consistent at approximately 80% for up to 800minutes TOS. Decarboxylation remained close to 60%, but increasedsomewhat when the gas flow was switched to Ar/H₂.

Run 5: Catalyst 1 was used for Run 5 with an oleic acid feed for thefirst 12 samples, and a palmitic acid feed for the last two samples. Thecolumn was operated at 295° C. with WHSV=0.36 h⁻¹ for oleic acid and0.37 hr¹ for palmitic acid. The column was purged with 3.5 mL/min of 92%Ar/8% H₂ for Samples 1-8, and 2.5 mL/min N₂ for Samples 9-14. Sampleacquisition times were 50-85 minutes.

The results of Run 5 are shown in FIGS. 24 and 25. Similar to Run 3, asignificant percentage of oleic acid in Samples 1-12 was alkylated andis not reflected in the yields shown in FIG. 24. FIG. 24 also shows thatthere was little difference in the products produced when the purge gaswas Ar/H₂ compared to when the purge gas was N₂. The palmitic acid seenin samples 1-3 is attributed to residual palmitic acid from an earlierrun on the column. FIG. 25 demonstrates that about 10-20% of the oleicacid feed was decarboxylated with the yield remaining fairly steady forup to 900 minutes TOS, with about 30% decarboxylation in Sample 1.

Catalyst 2 Analysis:

Catalyst 2 was used for Run 6. An up-flow, 6 cm³ column was packed with12.63 g of Catalyst 2. The temperature was initially 290° C., and wasincreased incrementally to 350° C. The column was operated at WHSV=0.34hr⁻¹ (0.9 mL/min.). The column was purged with 2.5 mL/min N₂ for Samples1-8, with no purge for Samples 9-33. A feed stock of 50/50 (w/w) oleicacid and palmitic acid was used for Samples 1-26. The feedstock waschanged to palmitic acid at the beginning of Sample 27 acquisition(after 287 hours time-on-stream). The column was run for a total of 367hours time-on-stream, with samples collected typically every 9-15 hours.

The results of Run 6 are shown in FIGS. 26-27. FIG. 26 illustrates theproducts formed when palmitic acid and oleic acid were exposed to thecatalyst. FIG. 27 shows the percent conversion of each fatty acid andthe overall percent decarboxylation as a function of time. Oleic acidwas 100% converted over the course of about 17,000 minutes TOS.Consistent with earlier runs, however, the oleic acid was not completelydecarboxylated and a significant percentage was alkylated to highermolecular weight products. Palmitic acid conversion was initially near100% but decreased with time. Increasing the temperature initiallyincreased palmitic acid conversion, but it again decreased with time.After the feed was switched from the oleic acid/palmitic acid mixture topalmitic acid, the percent palmitic acid conversion increased with time.The overall material balances were near 100%, but 30-40% of the productswere unaccounted for in the GC-FID analysis; presumably these were heavyproducts that were not detectable by GC. When the feed was mixed, thestearic acid yield increased as catalyst decarboxylation activitydecreased. After switching the feed to palmitic acid alone, thedecarboxylation rate appeared steady at 345° C. The material balancesand product yields were in good agreement, with nearly 100% of theproducts detected by GC-FID.

The gases produced by the reaction were quantified and are shown inTable 6. Gas concentrations remained consistent within each feedstock,while the total gas flow varied proportionally with the decarboxylationrate.

TABLE 6 50/50 Oleic/ Palmitic Acid Palmitic Acid Gas Component % (v/v) %(v/v) Propane 0.7 1.3 Isobutane Trace Trace N-butane 0.4 0.7 H₂ 11.718.8 CO₂ 83.0 69.1 Ethane 0.9 Trace CH₄ 1.5 1.1 CO 1.8 9.0

Catalyst 13 Analysis:

Catalyst 13 was evaluated for its ability to deoxygenate a stearic acidand palmitic acid mixture that was nominally 50/50 by weight in Run 7.An up-flow reactor with a nominal volume of 6 cm³ was packed with 15.94g of Catalyst 13. The temperature was monitored by a thermocouple placedat the outlet of the catalyst bed; the temperature reported is thereading at the exit of the reactor bed. The reactor was brought to aninitial temperature of 280° C. The column was initially purged with 2.5mL/min of N₂. The N₂ remained on at 2.5 mL/min for the duration of theexperiment. The feed was started with a nominal WHSV of 0.36 hr⁻¹. Tensamples were collected with collection times ranging from 3 to 16 hr.The reactor temperature was then increased to 310° C. Samples 11 through22 were then collected with collection times ranging from 8 to 16 hr.The reactor temperature was increased at the beginning of Sample 23 to330° C. Sample 23 had an acquisition time of 3 hr. At the culmination ofSample 23, the feed was stopped and the reactor was offline for 214 hr.During the time that the reactor was offline, the catalyst bed was keptat 100° C. and the N₂ purge was flowing. After the 214 hr offlineperiod, the reactor temperature was again increased to 330° C. and thetime-on-stream count started again. Samples 24 through 32 were collectedwith collection times ranging from 8 to 17 hr. The reactor temperaturewas then increased to 340° C. Samples 33 through 35 were collected withcollection times ranging from 9 to 15 hr. After collecting Sample 35,the WHSV was decreased to 0.31 hr⁻¹. Samples 36 to 39 were collectedwith collection times ranging from 9 to 15 hr.

Liquid samples were analyzed using GC and a derivatization techniquesimilar to the technique used in Example 1. Additionally, the gaseffluent was also sampled and analyzed with GC. These results areillustrated in FIGS. 28 a-b and 29 and Table 7. FIGS. 28 a-b illustratethat at a given reactor temperature, the catalyst slowly deactivatedsuch that palmitic acid and stearic acid eventually appeared in theliquid samples due to decreasing conversion. Raising the temperature ofthe reactor resulted in increased palmitic and stearic acid conversionas well as a greater yield of deoxygenated products (e.g. pentadecaneand septadecane). FIG. 29 shows that raising the temperature resulted inhigher decarboxylation rates to deoxygenated products. Table 6 shows theaverage gas composition of several samples at 330° C. and 340° C.

TABLE 7 Reactor Gas Effluent Concentrations vol %^(a) 50/50 50/50 FeedPalmitic/Stearic Palmitic/Stearic Temp, ° C. 330 340 H₂ 29 36 CO 10 8CO₂ 60 54 Light Alkanes 1 3 ^(a)N₂ concentration present from thecarrier gas has been omitted and the results normalized.

Example 3 Platinum/Carbon Catalysts Catalyst Synthesis:

Catalyst 1 (5 wt % Pt and 0.5 wt % Sn on C): A catalyst was preparedwith 5 wt % Pt and 0.5 wt % Sn on an engineered carbon support (HyperionCatalysis International, Inc., Cambridge, Mass.). The Pt and Sn wereimpregnated simultaneously. First, the calculated amount of SnCl₂.2H₂Oto give the desired percentage of tin (0.5 wt %) on the catalyst wasdissolved in a sufficient amount of HCl to prevent precipitation. Theconcentration of HCl is not critical, but is sufficient to solubilizethe SnCl₂.2H₂O. To this solution, the calculated amount ofchloroplatinic acid was added to give the desired percentage of platinum(5 wt %) on the catalyst. The solution was then diluted with anappropriate amount of deionized water such that the solution volumewould cause the support to reach incipient wetness upon impregnation.The solution was then added to the support. The catalyst was then driedin an oven set to 120° C. Next, the catalyst was heated to 300° C. at 5°C./min in flowing nitrogen for batch testing or helium for flow testing.When 300° C. was reached, the gas flow was changed to 100% hydrogen forbatch testing or a mixture of 8% H₂ in He for flow testing. Thetemperature ramp was continued to 500° C. and then held at 500° C. for2-3 hr. The catalyst was then cooled to room temperature under flowinghydrogen or 8% H₂/He gas mixture. When the catalyst was returned to roomtemperature, the catalyst was passivated with 2 vol % air in He.Immediately prior to usage, the catalyst was activated by reduction in aflowing stream of pure hydrogen for 2 hours for batch testing or 8% H₂in Ar overnight for flow testing at 150° C.

Catalyst 2 (5 wt % Pt and 0.5 wt % Ge on C): A catalyst was preparedwith 5 wt % Pt and 0.5 wt % Ge on an engineered carbon support (NoritROX 0.8, Norit Americas Inc., Marshall, Tex.). The Pt and Ge wereimpregnated simultaneously. First, the calculated amount of GeCl₄ togive 0.5 wt % Ge on the catalyst was dissolved in a sufficientconcentration of HCl to prevent precipitation. To this solution,chloroplatinic acid was added to give 5 wt % platinum on the catalyst.The solution was then diluted with an appropriate amount of concentratedHCl such that the solution volume would cause the support to reachincipient wetness upon impregnation. The solution was then added to thesupport and then dried at 120° C. in air. The catalyst was calcined,reduced, and activated before use or testing as described above forbatch testing.

Catalyst 3 (5 wt % Pt on C): A catalyst was prepared with 5 wt % Pt onan engineered Norit ROX 0.8 carbon support. Platinum ethanolamine (Pt-A)was used as the catalyst precursor. The Pt-A solution volume calculatedto result in 5 wt % Pt on the catalyst was diluted with deionized watersuch that the solution would cause the carbon support to reach incipientwetness upon adding all of the impregnation solution. The catalyst wasthen dried at room temperature for 15 minutes, followed by hot airdrying for 15 minutes, and finally dried at 120° C. overnight. Thecatalyst was calcined, reduced, and then activated before use or testingas earlier described for batch testing.

Catalyst 4 (5 wt % Pt and 0.5 wt % Ge on C): A 5% Pt/0.5% Ge catalystwas prepared using a previously prepared 5% Pt on an engineered Hyperioncarbon support. A solution of GeCl₄ in an amount sufficient to give 0.5wt % Ge on the catalyst was prepared in anhydrous ethanol of sufficientvolume to reach incipient wetness of the catalyst support. The ethanolicGeCl₄ solution was added to the catalyst until the incipient wetnesspoint of the catalyst was reached. The catalyst was then dried in anoven set to 120° C. A sample of the dried catalyst was calcined andreduced as previously described for batch testing. Prior to use thecatalyst was activated as described for batch testing.

Catalyst 5 (5 wt % Pt and 0.5 wt % Sn on C): A 5% Pt/0.5% Sn catalystwas prepared using a previously prepared 5% Pt on an engineered Hyperioncarbon support. A solution of SnCl₂.2H₂O in an amount sufficient to give0.5 wt % Sn on the catalyst was prepared with a sufficient amount of 6MHCl to prevent precipitation. The impregnation solution was then dilutedwith HCl (2-6M) to a volume such that upon addition of the solution theincipient wetness point of the catalyst was reached. The catalyst wasthen dried at in an oven set to 120° C. A sample of the catalyst wascalcined and reduced under the same conditions as described for thebatch testing. Prior to use the catalyst was activated as previouslydescribed for batch testing.

Catalyst Analysis:

Catalyst 1 was evaluated for its ability to decarboxylate oleic acid aswell as a linoleic acid/oleic acid mixture in Run 8. An up-flow reactorwith a nominal volume of 6 cm³ was packed with 2.90 g of Catalyst 1. Forthis experiment, the temperature was monitored by a thermocouple placedinto the aluminum block encompassing the reactor tube. Additionally, thetemperature of an aluminum block encompassing the feed pre-heater wasalso monitored. The pre-heater block and reactor block were brought toan initial temperature of 260° C. and 328° C., respectively. The columnwas purged with 2.5 mL/min of N₂ before beginning the oleic acid feed.The N₂ remained on at 2.5 mL/min for the duration of the experiment. Theinitial WHSV was 2.0 hr⁻¹. Samples 1 and 2 were then taken, each with acollection time of 3 hr. The WHSV was then decreased to 1.7 hr¹. Sample3 was drawn after a collection time of 12 hr. Next, the pre-heater blocktemperature was decreased to 54° C. and the reactor block temperaturewas increased to 352° C. Samples 4-7 were subsequently collected withcollection times ranging from 4 to 17 hrs. After Sample 7 was collected,the WHSV was decreased to 1.4 hr¹. Samples 8-10 were then collected withcollection times ranging from 6 to 17 hr. After Sample 10 was collected,the reactor block temperature was increased to 372° C. Samples 11-19were then collected, with collection times ranging from 5 to 15 hr. Thepre-heater block temperature was then increased from 62° C. to 75° C.Sample 20 was collected after 8 hr. The WHSV was then decreased to 1.0hr¹. Sample 21 was collected after 19 hr. The pre-heater blocktemperature was then increased to 75° C. Sample 22 was drawn after 26hr. The pre-heater block temperature was then decreased to 70° C.Samples 23 through 31 were drawn with collection times ranging from 22to 26 hr. At the beginning of the collection of Sample 32, linoleic acidwas added to the oleic acid feed such that the nominal composition ofthe feed was 50/50 by weight. Sample 32 was then collected after 24 hr.Samples 1-32 were analyzed via GC with a derivatization method similarto that in Example 1. Additionally, the gas phase effluent from thereactor was analyzed with GC.

The results of Run 8 are presented in FIGS. 30 and 31 as well as Table8. As shown in FIGS. 30 a-b, a large yield of “Others” was observed inthe liquid products. The “Others” category includes, but is not limitedto, cracking products, aromatics and branched products of the oleic acidfeed. FIGS. 30 a-b also show that decreasing the WHSV and pre-heaterblock temperature and increasing the reactor block temperature resultedin a higher yield of deoxygenated products as well as greater conversionof oleic acid. The results for Sample 32 in FIG. 30 a reveal that all ofthe linoleic acid fed was converted. FIG. 31 gives the combined level ofdecarboxylation and decarbonylation since CO and CO₂ were observed asmajor gaseous products. FIG. 31 reveals that the combined level ofdecarboxylation and decarbonylation remained reasonably steady betweenapproximately 300 and 500 hr time-on-stream. Table 7 reveals the averagegas composition of Samples 26-31.

TABLE 8 Reactor Gas Effluent Concentrations, vol % 50/50 Feed Oleic AcidOleic Acid/Linoleic Acid Sample Number 26-31* 32 H₂ 14 13 CO 22 22 CO₂20 19 N₂ 42 42 Light Alkanes 2 4 *The average concentrations of thesamples.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

1. A method, comprising: providing a catalyst comprising a) Pt and MO₃on ZrO₂ where M is W, Mo, or a combination thereof, b) Pt/Ge on carbon,c) Pt/Sn on carbon, or d) any combination thereof; exposing acomposition comprising fatty acids to the catalyst; and deoxygenating atleast 10% of the fatty acids with the catalyst to produce hydrocarbons.2. The method of claim 1, wherein deoxygenating comprisesdecarboxylating, decarbonylating, dehydrating, or any combinationthereof.
 3. The method of claim 1, wherein the fatty acids are obtainedfrom a plant oil, a plant fat, an animal fat, or any combinationthereof.
 4. The method of claim 1, wherein the composition is exposed tothe catalyst without added hydrogen.
 5. The method of claim 4, whereinat least 10% of the fatty acids in the composition are unsaturated fattyacids.
 6. The method of claim 1, wherein the composition is exposed tothe catalyst at a pressure of less than 250 psi.
 7. The method of claim1, wherein the composition is exposed to the catalyst at a pressure ofless than 100 psi.
 8. The method of claim 1, wherein the fatty acids inthe composition are free fatty acids, fatty acid esters, fatty acidmonoglycerides, fatty acid diglycerides, fatty acid triglycerides, orany combination thereof.
 9. The method of claim 1, wherein at least 90%of the fatty acids in the composition are free fatty acids.
 10. Themethod of claim 9, further comprising forming the free fatty acids byproviding a source of triglycerides and hydrolyzing the triglycerides toproduce the free fatty acids and glycerol.
 11. The method of claim 10,further comprising: separating the free fatty acids from the glycerol;and recovering the glycerol.
 12. The method of claim 10 furthercomprising hydrogenating the triglycerides before hydrolyzing thetriglycerides.
 13. The method of claim 1, wherein the compositionfurther comprises a hydrocarbon solvent.
 14. The method of claim 13,wherein the hydrocarbon solvent is obtained by recycling at least aportion of the hydrocarbons produced by deoxygenating fatty acids withthe catalyst.
 15. The method of claim 1, wherein at least some of thefatty acids in the composition are unsaturated fatty acids, and furthercomprising hydrogenating at least 10% of unsaturated bonds in theunsaturated fatty acids prior to exposing the composition to thecatalyst.
 16. The method of claim 15, further comprising storing thecomposition for a period of time prior to exposing the fatty acids tothe catalyst.
 17. The method of claim 1, wherein the catalyst is at atemperature of at least 250° C. prior to exposing the composition to thecatalyst, and the composition is not preheated before exposure to thecatalyst.
 18. The method of claim 1, wherein the catalyst is at atemperature of at least 250° C. and the composition is preheated to atemperature of at least 50° C. before exposure to the catalyst.
 19. Themethod of claim 1, further comprising disposing the catalyst within acolumn and flowing the composition through the column.
 20. The method ofclaim 19, wherein exposing the composition to the catalyst comprisesflowing the composition through the column at a WHSV of 0.1-2.0 hr⁻¹.21. The method of claim 20, wherein the WHSV is 0.3-1.0 hr⁻¹.
 22. Themethod of claim 19, further comprising concurrently flowing a gasthrough the column with the composition, wherein the gas is a) an inertgas, hydrogen, air, or oxygen, or b) a mixture of inert gas withhydrogen, air, oxygen, or a combination thereof.
 23. The method of claim19, wherein the catalyst remains capable of deoxygenating at least 10%of the fatty acids for at least 200 minutes at a temperature of 200-500°C. and a WHSV of 0.1-2.0 hr⁻¹.
 24. The method of claim 23, wherein thecatalyst remains capable of deoxygenating at least 10% of the fattyacids for at least 15,000 minutes.
 25. The method of claim 1, wherein atleast 80% of the fatty acids are deoxygenated after exposure to thecatalyst.
 26. The method of claim 1, wherein at least 90% of the fattyacids are saturated fatty acids and the catalyst is Pt and MO₃ on ZrO₂.27. The method of claim 26, wherein the catalyst comprises 0.1 wt % to1.5 wt % Pt and 6 wt % to 30 wt % MO₃, relative to a mass of thecatalyst.
 28. The method of claim 26, wherein the catalyst consistsessentially of 0.7 wt % Pt and 12 wt % WO₃, relative to the mass of thecatalyst.
 29. The method of claim 26, wherein the catalyst consistsessentially of 0.7 wt % Pt and 7.8 wt % MoO₃, relative to the mass ofthe catalyst.
 30. The method of claim 1, wherein at least some of thefatty acids are unsaturated fatty acids and the catalyst is Pt/Ge oncarbon, Pt/Sn on carbon, or a mixture thereof.
 31. The method of claim30, wherein the catalyst comprises a) 5 wt % Pt and b) 0.5 wt % Ge or0.5 wt % Sn, relative to a mass of the catalyst.
 32. The method of claim30, wherein exposing the unsaturated fatty acids to the catalyst resultsin cyclization and/or aromatization of up to 10% of the fatty acids. 33.The method of claim 30, wherein exposing the unsaturated fatty acids tothe catalyst results in isomerization, cracking, alkylation, cyclizationand/or aromatization of greater than 10% of the fatty acids.
 34. Themethod of claim 1, wherein at least a portion of the hydrocarbons areunsaturated hydrocarbons, and further comprising hydrogenating theunsaturated hydrocarbons to produce saturated hydrocarbons.
 35. Themethod of claim 1, further comprising fractionating the hydrocarbons toproduce one or more hydrocarbon fractions.
 36. The method of claim 1,further comprising utilizing the hydrocarbons as a fuel in an engine.37. The method of claim 1, further comprising utilizing the hydrocarbonsas an aviation fuel.
 38. The method of claim 1, further comprisingblending the hydrocarbons with petroleum fuel to produce a blended fuel.39. The method of claim 1, further comprising utilizing at least aportion of the hydrocarbons as a reactant in a chemical synthesisreaction.
 40. The method of claim 1, wherein exposing the composition tothe catalyst comprises heating the composition in the presence of thecatalyst at a temperature of at least 50° C., and wherein deoxygenatingat least 10% of the fatty acids is performed at a temperature of atleast 250° C.
 41. A method, comprising: exposing a compositioncomprising fatty acids to a first catalyst in a first catalyst bed at atemperature of at least 50° C., wherein the first catalyst comprises a)Pt and MO₃ on ZrO₂ where M is W, Mo, or a combination thereof, b) Pt/Geon carbon, c) Pt/Sn on carbon, or d) any combination thereof; anddeoxygenating at least 10% of the fatty acids by exposing thecomposition a second catalyst in a second catalyst bed at a temperatureof at least 250° C., wherein the second catalyst comprises a) Pt and MO₃on ZrO₂ where M is W, Mo, or a combination thereof, b) Pt/Ge on carbon,c) Pt/Sn on carbon, or d) any combination thereof.
 42. The method ofclaim 41, wherein the second catalyst comprises substantially the samechemical composition as the first catalyst.
 43. The method of claim 41,wherein the second catalyst comprises a different chemical compositionthan the first catalyst.
 44. A method, comprising: hydrolyzingtriglycerides to produce free fatty acids and glycerol; separating thefree fatty acids from the glycerol; exposing the separated free fattyacids to a catalyst selected from a) Pt and MO₃ on ZrO₂, where M is W,Mo, or a combination thereof, b) Pt/Ge on carbon, c) Pt/Sn on carbon, ord) any combination thereof, wherein exposing the free fatty acids to thecatalyst comprises providing a column with the catalyst disposed thereinand flowing the free fatty acids through the column without addedhydrogen, at a pressure less than 100 psi, at a temperature of at least250° C., and at a WHSV of 0.1-2.0 hr⁻¹; and deoxygenating at least 10%of the free fatty acids with the catalyst to produce hydrocarbons. 45.The method of claim 44, wherein the triglycerides are obtained from aplant oil, a plant fat, an animal fat, or any combination thereof. 46.The method of claim 44, wherein the catalyst is Pt and MO₃ on ZrO₂, andfurther comprising hydrogenating the triglycerides before hydrolyzingthe triglycerides.
 47. The method of claim 44, wherein at least some ofthe fatty acids are unsaturated fatty acids and the catalyst is Pt/Ge oncarbon or Pt/Sn on carbon.
 48. A method, comprising: providing acatalyst comprising platinum that is combined with a non-transitionmetal to facilitate dehydrogenation; exposing a composition comprisingfatty acids to the catalyst; and dehydrogenating at least 10% of thefatty acids with the catalyst to produce a product comprising branched,cyclic, and/or aromatic compounds.
 49. The method of claim 48 whereinthe catalyst deoxygenates at least 10% of the product.
 50. The method ofclaim 49 wherein at least 10% of the fatty acids are unsaturated fattyacids, and wherein dehydrogenating further comprises transferhydrogenation.
 51. A mixture comprising: a composition suitable for useas a renewable fuel, comprising: hydrocarbons in a liquid state; and atleast 1 part per million (ppm) Pt, W, Mo, and/or Zr.
 52. The mixture ofclaim 51, comprising at least a) 1 ppm Pt, b) at least 10 ppm Zr, and/orc) at least 10 ppm W, Mo, or a combination of W and Mo.
 53. The mixtureof claim 51, wherein greater than 70% of the hydrocarbons are C15-C17hydrocarbons.
 54. A mixture comprising: a composition suitable for useas a renewable fuel, comprising: hydrocarbons in a liquid state; atleast 1 part per million (ppm) Pt; and at least 0.5 ppm Ge, at least 0.5ppm Sn, or at least 0.5 ppm of a combination of Ge and Sn.
 55. Themixture of claim 54, wherein greater than 70% of the hydrocarbons areC15-C17 hydrocarbons.